Engine Masters - 3" single vs 2.5" dual

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Erik the Awful

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If you have Motor Trend On Demand access you need to head over and watch Engine Masters Episode 60 that just posted. They do a series of tests with single 3" and dual 2.5" exhausts, which pertains to most of us.

The takeaway: if you can run a single 3" exhaust with a Y merge and an open (i.e. see-through) muffler, do it. If you have to use a turbo muffler, a single 3" exhaust is going to give up serious power. I really would have liked to see them do a test with an X or H merge pipe on the 2.5" exhaust - I think that really hurt it in comparison to the Y on the 3".

To be honest, I was in the "duals are always better" camp. I just put dual 2.5" exhaust with cats, an X-pipe, and open mufflers on my truck.
 

PlayingWithTBI

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Interesting, I've read that unless you're pushing over 400HP, it really doesn't matter with either setup. I can say with my shorty headers, and JBA mandrel bent Y to 3" single high flow Cat, when I changed from a 3 chamber muffler to a 3" Borla Pro XS (straight through flow), I definitely gained some performance based on my SOTP (Seat Of The Pants) dyno.
 

Erik the Awful

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Yeah, and they do discuss that long-tube headers could change the outcome. They went with shorties on the test, thinking that most people who would opt for a single exhaust would also be limited to running shorties - I used long-tubes on my build. I'm hoping I'll make significantly more than 400 hp, but the realist side of me says, "probably not".
 

PlayingWithTBI

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