GenVibe - Community for Pontiac Vibe Enthusiasts

Why is the car seem slower with the new muffler. I have a full 2.5 header back exhaust with all magnaflow. When I have the stock rear muffler on the car she is nice and quite and hauls (removed). I put the Dynomax super turbo Hemi muffler and the car falls on its face off the line. I have reset the ecu and the car has instantly more torque with the stock rear muffler. Maybe there is something to back pressure. Also it has happened I am getting old because the car is to LOUD with the new muffler. An input on this would be great.

Could some one please close one of these threads

You'll have more back pressure with the stock exhaust, that's for sure. I'd put your new exhaust on and give it a few days to adjust, then make a judgment.

The car flies with the stock rear muffler. I will be waiting for a few days.

can you retune?i know with my set up, if i don't retune for it, it's pulling timing and everything else based on the old set up. with F/I you should be getting much better gains. when i went to a full TBE in August, it probably gave me another 20 whp. it was a substantial difference. not sure how the S/C would be, but i'd imagine it should still give you more power.

I am running the TRD piggy back ecu. I am going to try a smaller 2.25 turbo muffler and see what happens today.

first of all, sounds to me like you got a muffler designed for a V8, i bet that sounds like (removed)!

I think it is to it sounds like a freakin civic

Still working on the exhaust. I will keep you guys up to date on the new exhaust....

My guess is there was a drop in back pressure and a loss of torque kinda like when a header is installed for a lot of cars. I know I am agreeing with someone here on this on this thread so far...just cant remember who.

he didn't do a new header, he did 2.5" exhaust that started at the header.

I lost all back pressure too, when I went with a new exhaust. I have 2.5" stainless from the resonator back into a 1 in, 2 out muffler that is "ricey" loud. I will post pics when I get a chance. Anyway, with the loss of backpressure, my car has NO bottom end whatsoever, but it tries to spin the tires when it comes "on the cam" at about 4 grand:)

My understanding is that loss of low end torque is typical when you reduce back pressure. I haven't studied up on it (but I will now) but I have heard fairly often that back pressure does affect torque throughout.