Guest Jokkeri Posted April 5, 2014 Share Posted April 5, 2014 I have a JDM TT supra and at the moment it's completely stock except I have a nice flowing catback exhaust. With the car I got a downpipe with it that removes the cats also. It's a homemade pipe that has a weird inside diameter that seems to be around 55mm. I was thinking that it might be nice to just use that because it will probably also limit the boost to tolerable amounts so that I won't break the turbos... right? What I'm wanting to know is that does anyone have any idea is there any use for me to build a 3inch downpipe that has the 2inch restrictor ring? IF the small downpipe limits the boost to around 1-1.2bar... is there any loss of horsepower when using a 55mm downpipe compared to 76mm downpipe with the 50mm restrictor ring? Maybe the 3inch downpipe would help a little bit more because of the more space even though it has the restrictor ring? Just thought this up and got interested about it Quote Link to comment Share on other sites More sharing options...
Boxertricks Posted April 10, 2014 Share Posted April 10, 2014 Yeah it was something I considered when fitting my exhaust and decat, albeit without having a 55mm decat without a RR. Tbh unless you're going to go further than BPU on a JDM I wouldn't have thought it would make any difference considering the size of the restrictor ring and the fact that you don't want to be running more than 1.2bar of boost anyway. I've got a 3" catback with 2.5" whiffbitz decat and 2" restrictor...so the fact you've got no restrictor but a smaller decat shouldn't make any difference for BPU imo. Quote Link to comment Share on other sites More sharing options...
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