TurboXT Posted July 12, 2011 Share Posted July 12, 2011 Custom? Modded from new gens? Just catless down pipe and nice muffler? What is the best diameter to run? 3" too big? Let's discuss! Rick Quote Link to comment Share on other sites More sharing options...
[HTi]Johnson Posted July 12, 2011 Share Posted July 12, 2011 A lot of people run straight 2.5" pipe. Probably not legal in most states as it nulls any attempt at emissions. Now, offroad use is different. I ran 2.25" pipe with a flowmaster, it sounded alright, but a little too muscle car for me. A lot of people will say that you don't really have a size restriction after the turbo, as the turbo is all the backpressure you need. On a slight tangent: I've bell mouthed my downpipe and that made a huge difference for spool up. Quote Link to comment Share on other sites More sharing options...
carfreak85 Posted July 13, 2011 Share Posted July 13, 2011 I could tell you what I run (1.5" primaries, 1.75" to the turbo, 3" DP, 2.5" catless to a flowmaster American Thunder muffler) or I could point you to some information. I designed part of my exhaust (the header mostly) using info from these authors. They know their stuff and I trust their opinions and advice. Read and learn: http://www.motoiq.com/magazine_articles/articletype/articleview/articleid/900/how-to-make-your-own-effective-exhaust-system.aspx Quote Link to comment Share on other sites More sharing options...
TurboXT Posted July 13, 2011 Author Share Posted July 13, 2011 So, a 3" turbo back is not too big for the car then? Or would it be better to go sti dp, then 3" from there? My idea is to run a 3" bellmouth or sti dp, and have a custom 3" built with maybe a flow master/deltaflow dp back, that way I can swap back to stock for emissions tests fairly easily.... I'm also going to upgrade the turbo to a vf11 from a legacy ss. Rick Quote Link to comment Share on other sites More sharing options...
calebz Posted July 13, 2011 Share Posted July 13, 2011 I put a 2.5 inch trubo-back on my old wagon. Only difference I noticed between that and the crappy made 3 inch that was on there is that with the 2.5, you can't hear the turbo through the tailpipe very well.. Quote Link to comment Share on other sites More sharing options...
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