Wiretap

Yep, it does cool down, but any sudden step-down will add a restriction, if the stepdown has a sharp edge (such as the rim of a flange) the effect is squared.

That would be exactly what you don't want. 2.5" downpipe into 3" catback, 3" into 3" or 2.5" into 2.5". You don't want your exhaust diameter getting smaller towards the tail end.

My personal feeling is that 2.5" is the 'sweet spot', though I've seen good results on 2.75" systems on NAs also. As, on a turbo, a larger (assumedly better flowing) exhaust will create a larger pressure differential across the exhaust housing of the turbo it should result in a faster spool. In reference to before, the thing that makes the turbine on a turbo spin is primarily the pressure differential across the turbo, velocity will have some effect (which is why you don't want to run a bigger up-pipe) but that is primarily before the turbo starts producing positive pressure in the intake system.

I think your statements are a little confused / dont tell the whole picture. what you fail to acknowledge in the its full completeness of the working system, in that exhaust back pressure (or EGBP) post turbo definitely affects power and delivery. This is at odds with you're statement about pre turbo only matters. This then is at odds to the statement that you're looking for the max pressure differential across the turbo (which i believe is correct). Why is only one side important if you want the net across both sides? Smaller exhaust systems can cause a bottle neck in evacuating the gases once they have exited a turbine housing on medium to higher HP systems. This reduces your pressure differential and drops top end potential. This i am to prove just shortly going from a 2.5" mid to rear section (generating 7-9psi back pressure post turbo) to a 3" mid to rear freer flowing section - results of EGBP and power will follow. I'm openly not totally sure on pre turbo back pressure theory, but im also fairly confident you want maximum flow through the exhaust pre turbo (velocity) but nil pressure.. (But then in my head the 'pressure across the turbo' statement wouldn't make sense.) - I need to do some more reading. *note this discussion is applicable for turbo applications, NA is different! At no point did I discuss 'back pressure' in my response. Don't add words I didn't use.

I definitly noticed the difference and loss in back preasure when I wnt from the factory system to a 3" TBE, before the ECU was retuned. http://en.wikipedia.org/wiki/Back_pressure http://www.thumpertalk.com/topic/571594-exhaust-backpressure-the-myth/ Worth pointing out that in terms of flow velocity as mentioned in the latter article. In a turbo engine this only matters before the turbo. You want as much pressure differential across the turbo as possible to improve turbine efficiency and spool rate.

Typical quiet bigend noiseand Typical 'completely F*CKED' bigend noise

None. That's a myth that belongs to speed-density computed non-turbos.

Piston slap will start suddenly if you break the skirt off a piston, which isn't exactly the rarest occurrence around.

It's beneficial in some respects, but unless you're going for absurd numbers or make a habit of slightly overheating your engine it doesn't make too much difference in the long term.

8.5:1, you'll want to replace the very simple cast pistons with some 8:1 forgies. I'd recommend rods and new bearings too...

No idea. If it fits it should work.

Boschmann have been out for ages. They're a budget brand sadly, not known for their quality-of-reproduction.

Yep. so long as you're not using a BC/BF one which are different they're the same up to 2001 I believe.

Yup, bolted into the back of the front intake cam cap

Dead right. All GT sedans are auto, wagons could be either but still recieved a VF10 not VF8

Cam angle sensor should be black, not orange. I believe they're the same but they're coloured differently to distinguish them

Directly beneath the alternator, it's reddish orange after 1993, you can't miss it. Secured with one 10mm bolt.

The standard block on both RS and GT is closed deck. (In facelift models this may not be the case but this is just a rumour)

Seems the guy can't measure though, it's a 2.5" system. And rage stuff is often over the noise limit.

Nope, as above, pull the turbo and you should be able to get to it. Personally I'd recommend you replace the temp gauge first as they fail a lot more often.

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.

Yep, that's the oil pressure switch, which controls the oil light. Yours is on the back of the water crossover pipe.

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

Hang on.... Under the alternator... was the single-wire sticking up from the block or sticking forwards from the water crossover pipe? Sticking up is the oil pressure switch.

Replace the temperature gauge in the cluster.