GTP091 Posted July 31, 2012 Report Share Posted July 31, 2012 Before I buy some new magnaflow mufflers for my GTP (very soon). I`m wondering if my size should go up as I plan on doing a turbo down the road. I understand my 3.4 has 2.25" before the y and 2' after ( I measuured and mine is same). If I'm adding the turbo should I be using larger exhaust to help with turbo spool or does it really matter?. I would think less back pressure is good for a turbo system but I would think the same without it and that isn't the case; velocity is changed and affects scavaenging or something like that. Should I go 3 inch or just stay stock size? I guess Im just wondering if the guys with turbo LQ1's can tell me what they're using. I plan on using a high flow cat maybe a resonator and 2 magnaflows. It doesn't have a cat on there now but im kind of tired of stinky exhaust Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted July 31, 2012 Report Share Posted July 31, 2012 after the turbine housing, make all of the piping the same size as what's needed to fit the turbine exit(if you split it to do dual exhaust, then change as necessary). turbos do not benefit from pressure or flow restrictions after the turbine at all. Quote Link to comment Share on other sites More sharing options...
GTP091 Posted August 6, 2012 Author Report Share Posted August 6, 2012 The exhaust outlet on my turbo is 2.5" and so is the high flow cat from magnaflow that i'm looking to buy soon (23403) .I'll be keeping it 2.5" all the way to the y adapter if they confirm it's 2.5". Also nice to have this piece as it includes prebent downpipe and I can reverse engineer the turbo crossover from it. Stock loses 1/4" from single to split. So in picking the mufflers it would seem to make sense to go with 2.25" mufflers? the OEM tips on my car measure 1 7/8" outside so seems a weird measurement and doesn't match magnaflow muffler sizes. I''m debating changing tips as well but would like the option to keep them they fit the car when all shined up. I'm going to ask Magnaflow tech as well but do you guys think I should go 2.25" after the 'y'? also the 2 sizes from magnaflow for the mufflers are 4" X 9" (14325) or 5" X 8" (14225). I'm leaning towards the 9 X 4's but for no real reason. The mufflers on there now are 9.5 X 7 X 14" long. Any recommends here? Quote Link to comment Share on other sites More sharing options...
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