zx9

I'm looking at purchasing the FI downpipes. Just want to know how much louder the exhaust will be and if there were any noticeble performance improvements.

JMSIV

I think it will get louder, but it will be hard to say how much.

I still have not seen any dyno plots on any high flow cats. I would think they would have to make more high end hp, unless the flow rate exceeds the max allowed by the ECU and there is no increased fuel delivery. But it is not like you are supercharging the motor, so I doubt this would happen.

Of course, the best way to get the power is to have a remapped ECU which takes advantage of the reduced back pressure.

Vijay

on the RS4 motor.

FooFighterRS4

GMG originally planned to have downpipes and exhaust but scrapped the downpipes. I don't think they found any gains. They did have gains with the exhaust. I believe 10 hp to the wheel. I'm sure Ryne or Fabryce can clarify everything.

zx9

Well I was thinking about taking advantage of the sale FI was offering, but the common belief seems to be that downpipes won't offer much of a performance improvement...I'm happy with the loudness/tone of the GMG exhaust in its current state, but I just wanted to make sure (if I did end up getting them) that the addition of downpipes wouldn't make it too loud!

Maybe I'll look into doing the REVO mod instead.

zx9

which is very strange....maybe the gains, if any, aren't worth noting........

zx9

Yeah 8-10hp to the wheels with just the exhaust...

havabooz

i have the GMG now as well and im satisfied with its sound...any louder would make it a bit annoying for everyday driving, especially in the low rpm's

dp's are different from high flow cats...and unless you get resonated dp's they are completely pass through and will REALLY make it loud..and based on info below of little to no power gains, unless youre doing it for the increased loudness, dont do it!!

zx9

I'm happy with the sound as well and I don't want the car to be any louder unless the trade off is a significant performance increase.