[Conr4d]

I am curious if the size, shape, and design of a catless down pipe plays any role in throttle response and where power gains are made in the RPM range.

I’ve noticed there are two distinct types of catless down pipes designs on the market. VRSF, Fabspeed, and Akrapovic all share a straight narrow design that is similar size from opening to end. Whereas, Evolution Racewerks and Wagner have a much larger/wider opening with a bigger bend that flares into a narrower end. Do these distinct differences in size, shape, and design generate different results in terms of throttle response, back pressure, turbo spooling, and where in the RPM range power gains are made?

I have read that the straight narrower design decreases turbulence of exhaust gas and therefore increases exhaust flow and allows the turbo to spool faster. Yet, I have also read that the larger tapered design decreases back pressure and therefore increases exhaust flow and allows the turbo to spool faster.

My car is tuned Bootmod3 Stage 1 93 octane. After the down pipe is added, I may or may not upgrade the intercooler and go stage 2. Zero plans to upgrade the turbo or fuel pump.

Does anyone have any data or evidence to support that these down pipe design differences generate different or superior results? Drop some science and knowledge on me.

[AmuroRay]

Unlike NA cars, I dont think it matters much.

[mike@x-ph.com]

Power is the same, wider pipes in the center produce a deeper exhaust tone

[Conr4d]

Originally Posted by mike@x-ph.com

Power is the same, wider pipes in the center produce a deeper exhaust tone

Too funny! You read my mind, Mike. That was going to be my next question. Evolutions Racewerks it is. PM sent regarding stock/availability during these times.

[mike@x-ph.com]

Originally Posted by Conr4d

Too funny! You read my mind, Mike. That was going to be my next question. Evolutions Racewerks it is. PM sent regarding stock/availability during these times.

Got it