Factory mufflers..... power robbers?

[Forcefed86]

Currently I'm running a 3" DP no cats 3" pipe back to the factory twin mufflers. I do like the nice quest ride but I'm also wondering how much HP I'm losing out on. Have there been any dyno's on factory mufflers VS aftermarket? I'm really only interested in actual power loss and gains on paper. Not seat of the pants etc.

Thanks!

[Dramon]

You'll probably see some but I imagine most of your gain is gonna be with bigger piping.

I doubt you'd notice a big difference unless you were turbo and our cars don't seem to be too sensitive to backpressure.

[Forcefed86]

Just to clarify I am NA-T Dave H kit. I was thinking of a electric cutout and leaving the factory mufflers for the sleeper/nice cruise effect. Anyone done this?

[craaaazzy]

i did the same...running stock exhaust w/ electric cutout. here are my approximate numbers with no change other than exhaust:

open downpipe, i ran 15lbs
w/ stock exhaust put in place 8 or 9lbs
w/ cutout open, 13 lbs.

[Forcefed86]

No dyno numbers though I suppose?

[craaaazzy]

well, i dyno'd 310rwhp when at 8lbs with open down pipe. no other numbers yet though.

[Dan@FSM]

A car we did for a customer made close to 400whp (dynapack) going through 2.5"dp through stock SC exhaust on a Greddy 18G turbo, I forget boost level but maybe 22psi. Never dyno'd with aftermarket exhaust though...sorry so no comparison but I was amazed it made that considering the circumstances.

[dejacky]

I recommend upgrading your sc300 catback exhaust as soon as possible. After I upgraded mine, the engine revved faster, felt smoother, vacuum-to-boost transition was better, and drive-ability improved! If I had to guess as to how much power it added, I'd say no more than 20hp max. For the prior-mentioned flow-benefits, it's in your best interest to ditch the stock sc300 catback exhaust system.

Also, my JackyPerformance catback exhaust is no more than 5% louder than stock, so it's still very quiet, with ZERO droning effect.

[ElitistK]

another option is to run silencers (glasspack) as your muffler and delete the stock muffler. Straight pipes after turbo/cat.