Did some searching and couldn't really figure out what's up.

Hardware: Invidia G200 TD with Magnaflow X-Pipe

When the car is accelerating normally, the exhaust sounds perfectly fine. However if I put some load on it (i.e. flooring it in 6th gear at 50mph), then there will be a loud hissing sound.

Also, when not under load and the accelerator is fully down I also here it.

I used some high heat epoxy stuff (see below) to make the gaskets since Invidia makes odd sized pipes and won't sell me just the gaskets. Thinking that this was the problem I took the pipes off the car, re-applied the gasket sealent making damn sure there was enough to make a good seal, and put it back on the car. Sure enough the hissing was still there.

I called a local exhaust shop to have them take a look tomorrow. The guy said it doesn't sound like a leak, but wants to take a look anyways.

Edit: After the shop looked at it, there was nothing wrong with the pipes. No leaks in the pipes or gaskets.

 

don't use gasket putty. also, sounds like an exhaust leak. from a gasket possibly.

 

I didn't want to use the putty, but that was my only option. Invidia won't sell me just the gaskets and shops don't carry that size gasket around here. I tried about 7 shops in Fremont area.

This is what I used...

http://www.partsamerica.com/ProductD...egoryCode=2132

 

my friend had that stuff suck in the top of his HFC and ruin it once.

I don't get what is special about the gasket. don't you just order an OEM metal gasket from the dealer?

 

Its 50mm piping which is smaller then the OEM piping. Doesn't fit to my knowledge on this size pipe.

Edit: I am using the OEM metal gaskets between the front end of the X and the cats.

 

ah well. good luck.

 

my injen exhaust sounded like that also when i put it on... it kinda sounds like a spooling turbo, but like you said, only under heavy load.

i dont understand why it does this either... ive changed the gasket a number of times but it never goes away. i thought it was simply a by-product

 

Is it just me or is every other thread in this section about hissing sounds lately. I think there should be more than enough material to search by now. From what I remember, it's either a leak, the cross-over or H-pipe design, or very thin tubing.

 

1) Gasket - not it unless the material I used isn't sealing.

2) Cross-over design - Anybody with the magnaflow x-pipe have this problem?

3) Very thin tubing - anyone with a G200 have this problem?

 

I mean if you are just talking about the 'rattles in a tin can' sound, then it's probably rasp.

rasp and an exhaust leak are distinctly different.

 

Its definately not rasp. Like an earlier poster said, it sounds a lot like a turbo spooler, just a bit more "airier".

 

Exhaust shop said there was one minor leak on the x-pipe. Other then that it all looked good. Gaskets had a good seal, pipes were fine.

Unless the Magnaflow X-Pipe has a bad design, it has to be coming from somewhere else. Does anyone else with the magnaflow x-pipe have this symptom? Preferrably with 50mm piping.

 

Ok, so I hear this when the car isn't under load (when in idle and revving it with the "peddle to the metal").

Does anyone know the physics of the air coming through the pipes at the following scenerios:

1) low rpm's (accelerator not pressed to slightly pressed)
2) low rpm's (accelerator fully pressed)
3) high rpm's (accelerator not pressed to slightly pressed)
4) high rpm's (accelerator fully pressed)

 

its your intake making noise! I got that exact same sound, its the increased flow and my stupid injen intake making the sucking sound. The increased flow has something to do with this. Ive had 2 shops check for leaks...zero leaks. My car only making this sucking sounds when I get off the gas

 

That is def an exhaust leak. I had that same situation (6th gear and under medium-heavy load and gas). I found a leak between the manifold and test pipes, there was carbon buildup around the area.

 

I had this happen to me when i installed my test pipes. i know exactly what you mean. you said you have no leaks (as faar as i know. AAM checked my car couple weeks ago and said they fixed all the leaks). We think its a problem in my y pipe. the flex joint vibrates, making a hissing (rather really light vibrating) sound. Im getting a new y pipe and single exhaust this week so im hoping it will go away. Do you get the sound when you are decelerating in gear?

 

The sound is definately not coming from the engine bay. I have a microphone I'm going to run under the car to get a better idea of where it is coming from.

I didn't even think to check for carbon when I re-applied the gaskets . I will run for a few more weeks then take a look at the pipes again for carbon.

 

I am thinking its my flex pipe. I don't get any sound when i decelerate. The noise is in any gear accelrating with problably 75% or greater throttle.

1500-2500 is the loudest, 2500-4000 it's there but barely noticable, 4000+ it can be heard again, but drowned out by engine and exhaust noise.

I'm learning to live with it now that I dyno'd with successfull numbers.

 

Really does sound like what i had happen to me. the difference is probably x vs. y pipe. put your car on some jack stands and wait till it cools. Start up and check the flex joints to see if thats the problem.

Hope you figure the problem out.

 

what would I check for?