After Installing my helix catback and downpipe I have been hearing this very odd noise while accelerating. It only happens above 6000 rpms when Im accelerating hard. It sounds like high pressure escaping through a small opening, or kind of like a high pitched blow off valve. When i hear this noise I also feel a decrese in power. Im a newbie to turbocharged cars but would boost spiking, or something to that effect be causing this noise? Also would a leak in one of the exhaust connections cause a noise like this? Im realy puzzled to what it could be, any help would be greatly apreciated.

 

Sounds like the downpipe/turbo connection might be leaking. Is it from under the hood or under the floor?

 

Sounds like its coming from the engine so ill check the connection between the dp and turbo. I thought I got it pretty tight, but Ill try to re tighten it tommorow. Now that I think about it, it would make sense that there is a leak there. At first I didnt think that an exhaust leak could make that kind of noise but since it is right near the turbo it makes perfect sense now. Thanks for the insight, I hope it works.

 

I have the opposite noise. I installed my RSR Stainless cat bypassed downpipe. During idle I hear this whinning, whistling noise. It's not loud at all and as I accelerate, the noise disapears. I'm thinking maybe it's because I have no cat and the downpipe is pretty hollow in there.

 

Shouldn't lose power even if it was leaking, specially not at 6000rpm. You probably already know but turbo exhausts gasses run differently than NA cars, they are volume not velocity dependent, NA is the other way round. HVe tou got a boost gauge? Does it drop off at 6000rpm? And is the exhaust 3" from the turbo back? Sounds like a waste gate related problem.

 

Could be a boost leak due to higher boost now when running 3" exhaust? Check all hoses and pipes from the turbo via the intercooler and to the intake.

 

Is your air intake scoop properly secured down? Mine made a similar noise at high rpm/full boost and it was because those cheap plastic clips had come off and the intake was getting sucked up into the hood and choking the motor.

 

That's not from the exhaust install. If you had a exhaust leak you wouldn't lose power. Check all the vac lines and I/C pipe clamps. Also do you have a upgraded intake and or BOV

 

Actualy it isnt secured down properly, my two intake clips are also broken. Ill try to secure them down and see if it still does it. I have a feeling that its not the problem since the clips were broken before the exhaust install, and never made that noise.
Its funny because it doesnt make the noise all the time. It only occurs about 25% of the time when i accelerate hard. Im gonna make sure all the connections are tight, and secure the air intake and see if it still does it.
Oh yea one more thing, I have a stage rev flash from dyno flash which eliminates the boost taper in the high rpms. Do you think it could have anything to do with that?

Again thanks for your help