exhaust - 3 inch or 2.5?
 

hi all - I have a 2002 wrx turbo engine which I have fitted to my camper (see the projects section for details) obviously im in the position of having to build my own exhaust system but Ive got meself all confused with all the options out there........

I want:
something that makes the most of the subaru sounds (subtley tho)
something that doesnt comprimise performance
something that is bearable to drive long distance - its a camper rememebr so its going to be on long road trips and its also a box shape which is prone to booming.

I have:
A twin mouth decat down pipe which is 3 inch tapering to 2.5 at the join.
an evo 9 mid section with slimline silncer box (3 inch)

The problems:
1) I have to cut the downpipe up and reweld it to desired shapes so.... do I stick with STD 2.5inch taper or do I loose the taper and run 3 inch? Will there be any merit in gainig the .5 inch?

2)Whichever option I go for I will prob need to run an intermadiate box - I have a mid pipe from a Evo 9. I wonder will this be enough to silence to required level with something like a magnex 6x3 oval tailed backbox? would I be better to run a big fat intermediate box instead?

3)as for the 'back box' well its going to be a side exit exhaust system (just in front of rear wheel with an oval tip magnex or similar as they are quite narrow top to bottom- the reason for this is ground clearance issues and also simplicity of the system (no routing through suspension etc) - will the magnex with an intermediate box result in the type of 'noise/performance balance i want?

Ive been recommended a prodrive back box and this is the level of noise I want to achieve - a subtle rumble - but these are very tall boxes so are no good but do provide the end result on the sort of noise/performance balance i require - so i guess the question is - what components are recommended to get similar results without compromising my ears or the engines performance.


Cheers
Rich