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An idiot's guide to hotting up your TT legacy


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(I'm going to edit this and link to stuffs so it will change but call it a beginners guide to legacy things)

(Also when I say idiots' guide, I mean me writing the guide... I'm not calling you, dear reader, an idiot. Yet)


You've got yourself the classic family wagon for the man who likes to overtake 5 cars at once, but you want more don't ya

Yeeeeah you do, you non reformed boy racer bogan in hiding you

But you don't want to spend much do ya?

Well LISTEN UP here's how to do it

So first up we'll assume you have the necessary prerequisites: A sweet-ass legacy RS, GTB or B4 with that super rad twin turbo motor, and that no other ****er has toyed with it before you got your capable hands on it

So what I'm here to do today is show you a bunch of sheez you can do for not much coinage, in the backyard DIY form, and the higher budget versions, then the free stuff

1: Airboxy stuff: This depends on your bogan tendencies. Option A, is to get allll up in the inner guards' business and rip out that great big resonator type thingy, and let the airbox breathe directly from the inner guard. Some folks like to get all overexcited and make up an air intake down to the bumper but that's literally work for no gain, it's already ambient temperature in the guard

Option B and my pick is a pod filter on the end of a pipe in the guard, reason being you get all the cold airyness BUT with the added bonus of sweet sweet turbo sucky noises

Net cost: $free to $300 for a bespoke in guard unit meant for WRX from MRT / COBB or the likes

Net gain: Probably some horseypowers? Maybe a torque or two

2: Air intakey bit: This is a cheap bit to upgrade which if nothing else is a primo placebo and looks pretty - the intake pipe bit after the air flow meter has an ugly ribbed bit (not for her pleasure), replacing this pipe you have a couple options. A) is a $$ zerosports pipe, it's metal and costs $3 to make and $150+ to purchase. Option B is a silicon pipe from STA parts for $45 which achieves the same smoothing at a third the cost.

There is ALSO an intake pipe for the under manifold you can buy on ebay for about $300NZD - search "legacy induction" and you should find it. Feedback on here suggests it is worth doing, just a little more time consuming and tricky to fit.

Net cost: Not much to $350 tops

Net gain: Not much either but much better sucky noises and it certainly doesn't lose any

3: Turbos: If you don't have them already, VF26/27 are the gun combo to get from a cost vs gain perspective. They'll bolt on to any of the earlier models just fine, whack it on there and go nuts. There are hybrid options available by boring housings and all sorts of crazy shenanigans... Don't do that, you have to spend moneys better spent on doing something better. A manual B4 should have these already (or facelift gets VF31/33 which is rough enough to the same).

I have had success in putting the VF27 BB core into a VF26 exhaust housing to create a ridiculously fast spooling primary - like 2000rpm full boost type fast - it is literally as simple as clocking the front housing, drilling it to suit the wastegate actuator, and bolting it into the VF26 exhaust. I did it while the old turbo housing stayed on the car in an afternoon and was worth the fiddling involved.

If you need more turbo flow than what these can provide, you may as well go to a single unit far better suited to a 2l 4cyl motor.

Net cost: At most, $200 each?

Net gain: Depends how much power you didn't have before I guess but VF26 & 27 are capable of 200wkw when asked nicely

4: Intercooler stuffs!: People argue this a lot. People ALSO argue about global warming by ignoring facts in their faces so take what you will from that, I'll share what I have done and found myself.

The stock cooler itself isn't bad - on any year TT it's the same as the equivalent STi intercooler which is no bad thing. It's also a tiny unit sitting directly above two hot exhaust housings so heat soak is always going to be your enemy. Upgrades are simple, and cheap.

Option A) - Keep the stock cooler, replace the intercooler hoses with silicon pipes, or even radiator hose or whatever. The stock pipe necks down smaller than the primary turbo outlet, and is ribbed (again, not for her pleasure). To replace these pipes you need a 45' bend, and a 90' bend, ideally a reducing one from about 1.25" to 1.75" - or you can stretch and compress a 1.5" one, whatever floats your boat. This is a cheap mod which numerous folks have done and noticed an instant perk up in response and maybe kinda power too? It's worth it for the $$.

Option B) is spending big money on samco bespoke pipes which noone can see except your own wallet.

Option C) You CAN fit a V7 STi intercooler there. It's pretty tight and doesn't really want to get in there, but after it's in there and all the kicking and screaming is over it kinda looks like it's meant to be there and you wonder what all the fuss was about.

That's what she said

No but really it does fit, it's tight to the firewall and you need new intercooler hoses, and a very short turbo - throttle hose, but it fits. It's thicker, wider, longer, and does work better - the problem is that your bonnet scoop only covers 3/4 of it. Take this into account as it's semi pointless putting a bigger core in without cooling it. It will also hit 80deg just sitting in the KFC drive through so while good on the road... Not ideal in traffic. It doesn't remove the key Subaru handicap.

Something you can do with all the top mount coolers is a fan underneath - these are like $30 on TM and meant for small radiators or oil coolers - I tried it, and it works (pulling air downwards) - it does mitigate the heat soak issue. Not completely, but it does help and in my view is worthwhile if you're persevering with a top mount. Especially valid if you fang it from a standstill now and then...

Option D) My pick is just put a front mount on it. I noticed literally zero increase in spool up lag, and genuine decrease in the dip during changeover time, and markedly improved performance & mileage. You can either buy the bolt on kit from Scarles, or you can bastardise a WRX kit to work - up to you but it's something I can't push strongly enough. I'm yet to drive a legacy which felt "more laggy" due to a FMIC, it only has positive results. It resolves all heat soak problems, and removes a big chunk of the dip in the middle. ALSO gives you those sweet BOV chchchch noises which be honest, are pretty awesome

Moolahs: $50ish for just changing the pipes, $250ish to put a V7 STi one on there, $250-500 for a FMIC kit

Gains: All the gains. Solid power gains to be made and massive economy & driveability gains from losing the heat soak which plagues these beasties

5: Exhausty things!: This is easy and pretty generic to any turbo car

Bigger is better, my advice is keep an eye out for a 2.5" or 3" system off a wrecked car (www.subaruspeed.co.nz is a gold mine) and bung it on. Don't reinvent the wheel with a custom job unless you like blowing $ on useless ****.

DOWNPIPES you need thems fo SHO - again just keeps an eye out for some. My personal favourite is just cut the cat out of the primary DP and be done with it. 93-03 can all share a pipe BUT there is a difference between manual and auto.

Cost: More than $300 and you're doing things the hard way

Gains: I have no idea, a bunch tho they really do wake up with an open exhaust and the noise oh god the noise

6: Computery stuffs: There are a few trains of thought here. Most don't touch it, or chuck in whatever pre-tuned ecu they can find ex japan and hope it's sweet. It's an option and half the time a good one. the other half it pings to death so YMMV. Err.... good luck there. Once upon a time people had success with tuning these via an S-AFC to get a bit more power and economy out of them, it's worth doing if you have someone clued up with the ability to datalog or want to pay for a couple hours dyno time.

Now there's a doohickey called a Zerosports Sequential Controller floating around. What it does it let you fiddle the switchover time to make it happen faster and when you want.... My personal suggestion is fck that and do Rossubseses restrictor thing and just get the factory setup to behave a bit better - you can get the car to behave very seamlessly with a little patience, plus the ZS controllers seem to be a mixed bag of error codes and confusion. Combine this with adjusting the throw on the exhaust valve (explained below) and you can fine tune out the fumble of an effort subaru made out of the box.

If you have a revision D B4 or GTB you can reflash the stock computer - watch this space I'm trying to work it out myself and will link a guide when I get it to fcking work. Earlier models can be retuned with an "ESL" daughterboard but cost is... Cost is more than a single turbo conversion costs and the gains are less.

Cost: $0 for DIYing that shiz to $1200 for a proper tune (plus?)

Gains: Pretty reasonable AND you cant put a number on smoothing the power out can you

7: BOOSTY BOOSTY: The factory setup works good, to a point - it gives approx 10psi on the primary and 14ish on the secondary out of the box, with a lazy spool up on the primary and a tendency to shoot for the moon when modified.

I say fck that nonsense you need more and you need it NOW

To be really blunt the less you spend here I reckon the better it works. A "dumb" $20 boost tap teed in a direct line from turbo to wastegate will let you dial in a nice comfy 16psi, which you'll see from 2500 to 7500, and do it all day. Or you can attempt to get an electronic one to cope with half the boost falling off in the middle, before it recovers and overshoots later, and just becomes an abortion of confusion and wasted money

Do what you want but I know what I'd do

The internet tells tales of primary turbos blowing up, the internet also tells stories of little johnny being the next D1 king so there's that

Cost: .50c for a home made boost tee to $900 for a blingspec electronic job

Gains: Up top, probably nothing unless you crank that needle right round. Midrange fckin HEAPS to gain with some decent pressure in there


First thing to mess with if so inclined is the ECV valve. That's the big bugger on the drivers' side. Now look underneath it, it has a threaded rod leading down to something foolish way under the turbo. Now what you can do if so inclined is fiddle this to give either a faster spool up to twin mode, a faster spool up in single mode, or something right in the middle. Wind it right out - fast secondary spool, and you lose half your bububub noise - thats' cause you're bleeding exhaust gas through a turbo which is currently blocked off from the intake. Wind it right in, and you'll find the switchover takes a little longer BUT it probably felt pretty punchy up till 4500 yeah? That's cause it's held super tight shut. My advice is wind it about 2/3 out, at idle you can wind it to a point where it juuuuust starts to rattle - from there go a turn or two back towards closed. It gives the best midpoint of primary and secondary spool, however it depends on your driving style what you'd rather.

The "Hose 10 Mod" . Short version is it makes the car far punchier, by removing a factory designed intake leak... that's the long and short of it. Nothing to lose, everything to gain. http://clubsub.org.nz/forum/showthread.php?34317-The-Hose-10-Mod-BE-BH&highlight=hose

Rossssses sequential timing mod: Again I'll link it here - this is putting a tiny restrictor into one hose, makes the switchover far smoother by slowing down one of the changeover valves a touch. Net result - no more massive dip at 4500rpm and zero ill effects http://clubsub.org.nz/forum/showthread.php?40911-Inside-the-BBOD

Running in parallel: It's a little bit spastic but you can do it if you like, it's pretty painless, free and reversible, if nothing else it gives a point of difference and a very different car to drive, basically gutless under 3500 then both spool and give you the same speed you had before anyway. http://clubsub.org.nz/forum/showthread.php?32559-Idiots-guide-to-converting-your-legacy-to-parallel/page2

Moneys: I already said free DONT YOU LISTEN

Gains: Well, none, but you get to go fast where before it wouldn't, so that's a gain? You gain a smile. There, that'll do.

There are some other things floating around - but to be honest I can't think of much more I'd do with one of these which isn't effectively just frittering money away into uselessness... Go to a single, simply because it's a very cheap and straightforward swap. If you don't, the simple bolt on changes will still net you a solid 170-190kW @ wheels car which while not quite ideal out of the box, can be made far better with a couple of well thought out tweaks

Also with no cats or BOV they pop some sweet backfires

I'll edit this tomorrow most likely

Edited by Marky
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I have:

Blitz Pod filter

Upgraded turbo-intercooler pipes

Vac lines replaced

Hose 1 restrictor

Rage downpipes, y pipe

FGK high flow cat, centre and muffler

Gizzmo IBCR boost controller (fails hard, should have kept the factory boost control)

Raijin Tune

This makes me 200wkw at around 20psi.

Lots o suspension mods as well.

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Lachlan: No mine normally sit dead steady - that said my new purchase is starting to creep above 6500 without the DP cat gone so time will tell, might also be my bodged up boost control yet

Skatieguy: Yes, but you need to adjust it with it running to get it just right. You'll hear the sound change as the valve creeps open.

RobMinhas: Err, just your normal trademe/ebay subaru front mount setup but with a Y pipe

Joker: Are you drinking and typing and can you sticky this once I make it look pretty with links and stuff

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Not sure on duty @ 20psi. Boost cut is something like 25psi on the tune I have. Have hit it a few times in 4th gear full load. Stupid boost controller does whatever the hell it likes, totally disappointed with it.

Primary boost level is messed up at the moment as well. Got the feeling something isn't right with the crossover as it will boost 20+ when disconnecting hose 2(?).

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  • 3 weeks later...
 GorGasmSpecB said:
Not sure on duty @ 20psi. Boost cut is something like 25psi on the tune I have. Have hit it a few times in 4th gear full load. Stupid boost controller does whatever the hell it likes, totally disappointed with it.

Primary boost level is messed up at the moment as well. Got the feeling something isn't right with the crossover as it will boost 20+ when disconnecting hose 2(?).

Hose #2 is the boost feed for the ECV positive side, which runs a constant duty cycle during primary boost. So disconnecting hose 2 will stop the ECV opening during primary boost and send all exhaust gas through the primary turbo.

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  • 1 month later...
  • 4 months later...

So I did some tinkering this weekend and figured I'd add to this, also bumping it to motivate myself to finish/edit the first post

So there's a thing you can do with the ECV valve to make it pre-spool in a self-regulating sort of way, the basic idea of it is taking away the ECU control of the positive side of it - the computer still controls the negative pressure end of it, which does 80% of the "pulling" it open. It's an idea I read online here http://www.subyclub.com/topic/8678-tt-no-boosthelp/page-3 , which I tried, it works, and added to it cause I have too much spare time.

So what you can do is get a little creative with this. Takes a bit of trial and error to get it just right, but it accompanied with Ross's hose restrictor stuff nets you a really nicely driving car.

Theory: The ECV is pulled open by the ecu primarily, using the big negative pressure tank in the passengers' side guard. There is a positive pressure side too, but it is just used to assist so to speak.

So what you do is take the little hose to the top of the ECV, unplug it from the big box of bullsh!t (BBoB) on the left, and instead give it a positive feed from... anywhere. Tee it off your BOV or boost gauge line would work fine. Added benifit there is it gets negative pressure on throttle off, helping pull it shut in a hurry and reducing time spent getting back on primary only if you shift in the dead zone.

Now what you'll find is you lose a bit of primary spool, and you'll hear the exhaust note change with boost... What's happening is the valve is getting pushed open a bit, not all the way but a bit, when you have the primary awake - it's sending some flow through the secondary now too though.

You need to fiddle with the ECV rod underneath a bit to try to balance the pre-spool just right, when it's right you get a much better transition to twin mode and much more linear power, especially that first couple times you wake up the secondary from cold(ish).

The OTHER way to do it, which I prefer and tried, is to do exactly all the above, but put inline to it a pressure activated solenoid (a stock subaru boost control solenoid, wired in series to a $5 pressure switch will do it). Set to say 5, or 8psi, you now have all the part-throttle go you always do, BUT if you ask for full boost it'll start the pre spool. Hell if you wanted to you could even put that on a switch to let you choose if you want it killed off (say if you're towing, or just like that adjustability). With the top port left vented, so inactive, the difference in how it changes over is almost impossible to pick up - but WITH the above fiddling applied it can be quite useful.

Better living everybody

Edited by Marky
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