hey guys, I have a custom axel back with a greddy evo 2 catback muffler and the rrm downpipe. without the downpipe it sounds smooth and normal. with the downpipe it it sounds raspy (as it should) but around 3 to 5 k rpms under moderate to heavy throttle it rattles and sounds horrible. it only does this with the downpipe in. i really would like to keep it in but i cant stand having my car sound that cheap. i've checked all the welds and the gasket in between the mid and downpipe. no leaks and the pipe is not hitting anywhere. can someone tell me why this is doing this to me and what i might be able to do to fix it?
thanks
-cameron

 

mine did the same thing too at 3500-4000 rpm, It was caused by the muffler. I first had a magnaflow...then switched to a flowmaster which made it worse. I ended up getting a custom STETBRO($300) 18x12x6, this cleared up the sound. The DP increases the flow alot and this creates resonance throughout the whole system. I also have an inline resonator by STETBRO 10x4x6. Its still a little loud, but its the best sound I could manage

 

Do you have any idea whereabouts along the exhaust line that the rattle occurs? I don't have this, and I wonder if it's because I use poly exhaust mounts from the downpipe back.

 

at first the rattle was directly under my shifter leading me to believe it was the donut between the down and mid pipe but after checking this and sealing it with silicone the sound has now moved to the rear of my car. as i said before im sure its not a leak, and it probably just as something to do with the increased flow, i just didnt know if there was anything i could do about it, short of taking the downpipe out.

 

Sounds like the flexpipe problem to me.

 

I just started having the same problem with my magnaflow catback. Its super annoying. It rattles right below the shifter from about 2500-4000 rpm...

 

yup sounds like the same problem... im about to just rip the exhaust off from the header back and deal..... its that annoying

 

Guys, guys, I researched this very same problem on my sportback and here's the solve:

Put a BIG resonator in place right after the end of the downpipe, and go custom all the way back to a magnaflow performance muffler. I'm running (two) big resonators - I'll take a pic today while my car is on the lift. There was no power loss at all and it sounds incredible.

My ride with the resonators to keep it a bit quieter has a DEEP rumble now and you can still hear the intake roar when you stomp the throttle. Even over the exhaust. The intake roar catches people's attention frequently. When you start the car outside you can feel it in the ground. It's pretty sexy actually...:-D

It's an EASY fix, and with Downpipe and complete custom exhaust in Canada everything cost me $450 installed. My car is linked in my sig. I'll add more pics to that page later today when I'm done at RRM. :-)

Don't give up on the downpipe, just toss in a resonator and your life will be much easier to deal with.

Mad!