Help find my missing power.

[AdamOst]

For under 200kw i shouldn't be held back by 2.5inch thought should I?

I was hoping to keep away from front mount, but I guess if i need the extra cooling I will have to do it.

Didnt realise the exhaust would net me a near 50hp gain, is the stock one really that bad? I quite like how quiet it is on the motorway then a bit louder when thrashing it.

[WRXONP]

 AdamOst said:

For under 200kw i shouldn't be held back by 2.5inch thought should I?

I was hoping to keep away from front mount, but I guess if i need the extra cooling I will have to do it.

Didnt realise the exhaust would net me a near 50hp gain, is the stock one really that bad? I quite like how quiet it is on the motorway then a bit louder when thrashing it.

you dont need a front mount - but the extra cooling makes the air more dense and also helps prevent detonation

as for exhaust like i said - 2.5 inch vs 3 inch - 3 inch has more flow so will net more power

the stock rear muffler adds trimendous back pressure as does the catalic converter

i ran a 3 inch down pipe -3 inch mid pipe and a 2.5 inch diff back and 2.5 inch ID muffler - made 200kw - with the 2.5 inch at the rear it basically restricted the exhaust to only flow as much as a full 2.5 inch - i remade the rear section into 3 inch with a 3 inch ID muffler and re ran on same dyno (torque) made 15kw gain and power curve moved left (turbo spooled faster)

[AdamOst]

Hmm you have given me some stuff to think about. Thanks.

[sultan]

your power is down because you're running less than stock boost. simple. either take it to some one who knows subarus well, or install a boost tap or something if you cbf with that

[AdamOst]

 AdamOst said:

Recommendations for places on the north shore of auckland i could take it to?

-e- What is stock boost actually? Ive seen both 15 and 17psi thrown around but never a confirmed number.

[WRXONP]

ver 3-4 sti stock psi is up around 16-18 depending on exhaust

the ver 3-4 is lower compression than the ver 5-6 which stock is 14-16 depending on exhaust

a more free flowing exhaust will raise the boost as the duty cycle on the solenoid will stay the same - but with more flow it will do higher boost

to me - boost and power isnt lower than normal - unless someone has another stock one to compare too

[AdamOst]

So on the exhaust side how much am I looking at paying for a 2.5inch turbo back? either to buy or fitted as well as a rough amount. Any recommendations on a shop in Auckland? preferably north.

[WRXONP]

second hand will get u one alot cheaper than new

full mandrel bent exhausts from pitstop are normally around 1000$ give or take

[Wiretap]

The guy who made the top power of the day is selling a 3". Avoid exhaust shops unless you like em chopped and botched.

[AdamOst]

Yeah have seen his. Wasnt too loud iirc as well so could be an option. Are they normally a straight swap/unbolt to install? i have limited mechanical ability but am fine with learning Or will I need ot get it welded up.

Otherwise something like http://www.trademe.co.nz/motors/car-parts-accessories/subaru/other/auction-472461347.htm ?

[WRXONP]

teznu's would be perfect for you - as its a jasma spec rear muffler - which are normally great flow - but stop allot more noise than a convectional cannon muffler

i run a HKS exhaust on my silvia which is jasma approved and its fairly quiete on idle for a 3-4 inch exhasut - its only loud when your hard on the gas

[AdamOst]

Yeah id prefer something like that, a bit more discreet than a big cannon. What's involved in installing it?

[Wiretap]

It's a Kakimoto, it'll be a bolt in jobbie. That china-cannon will be probably quite loud.

If you get something I've got a fair bit of free time at the moment, can give you a hand fitting it up. I know my way around an Impreza quite well.

The most difficult bolts will be the ones on the back of the turbo, they're a pig when they've not been released before.

[AdamOst]

That would be awesome thanks. Im not completely useless but my current house doesn't allow much in the way of car workshop steez, first car ive owned thats worth actually doing anything too haha. Ill hit up tez and most likely buy it. And will need to arrange to transport it as unless it brakes down to small bits my rex is a bit hopeless I think.

[Wiretap]

It'll split down into 3 bits (downpipe, midpipe, tailpipe/muffler) and fit in your Impreza, I've transported a few that way.

I have plenty of space and a couple of things you might like to see

[Guest]

it doesnt come with downpipe...

[AdamOst]

Legend.

Seems ot be downpipe back so will need to buy a down pipe as well i assume as itll be a bit fo a waste on the factory one?

http://www.trademe.co.nz/motors/car-parts-accessories/subaru/other/auction-472492998.htm any good?

[Guest]

downpipes the important bit. you can pick them up cheaper secondhand though.

[Wiretap]

Bellmouth seems to be all the rage these days, but Divorced (siamese) or Split-tube are better. (split tube has a seperate tube for the wastegate that joins in down near the bottom)

[AdamOst]

if i can find one before i get the rest of the exhuast second hand would be good but if not ill have ot buy new. Need ot get it sorted before taupo next month

[slystiguy]

jap race sold one to me ages ago for 250.3inch chromed bolt on downpipe seemed to be decent quality. for ease of installation be sure to get one with the oxy sensor in the right place

[Guest]

the split tube type dont normally match the flange though i imagine the restriction would cause a bit of disturbance. i had a new scarles one but went to twisted. go divorced if you can or bellmouth.

as above check 02 sensor location the driven one only had it at the rear.

im running external with bell mouth just keeps the exhaust off the exhaust housing a good size rather.

dansco auto on tm have systems cheap too.

edit: http://www.trademe.co.nz/motors/car-parts-accessories/subaru/accessories/auction-473305810.htm

[Wiretap]

That's a 2.5", it will not fit a 3" exhaust.

[Guest]

i didnt ask but was more just so he knows who i was talking about they wreck a lot of fresh imports.

i think my 3" catback bolted up to standard dp but wouldnt do it the other way though. the weird flange/cone gasket that subaru use is about 3" on cat side by memory so it slips over top then reduces to 2.5" you would need a 3" universal gasket though.

im about to rebuild mine but the old catback ones quite rugged and wouldnt have a tip.

full system local with good rage tip

http://www.trademe.co.nz/motors/car-parts-accessories/subaru/accessories/auction-472642325.htm

[Wiretap]

The carbon ring will not seal properly if you attach it to the wrong sized exhaust, it might work but it doesn't make it a good idea.

Strong For Subaru may have some downpipes available. Give them a ring and speak to Gerald.