Rattlesnake Exhaust.

[brods2151]

Just finished off my exhaust with some high flow cats, only problem is now when i accelerate it literally sounds like a rattlesnake under my car. Ive tightened everything all the screws and bolts etc.
Its most prominent on a cold start and quietens as the exhaust heats up but is still their.
Took it back to the exhaust shop and they just said that its the resonance of the exhaust gases.
Anyone heard of anything like this?

Cheers.

[stubberzz]

i had the same problem , turn out that it was the heat shield

[brods2151]

Did you remove the heat shield or find some way of securing it?

[stubberzz]

its usally just a loose heat sheild check to make sure , if it is just tighten it

[Benboy]

Also check to make sure you don't have any loose baffles in the exhaust or foreign bits left inside at time of manufacture.

[brods2151]

Not really keen on taking my exhaust apart, when i start touching things they seem to break =)

[Not_An_Abba_Fan]

The problem could very well be the two resonators under the car that looked like cats. They are there to take out the 'raspiness' of the exhaust. Put them back in or use a couple of hot dogs just behind the cats and it should fix it.

[brods2151]

My system consists of Pacie extractors, High flow cats of some sort. A middle muffler and a rear resonator.
Just been to a local exhaust place and they said it might be the fact that i have twin tips welded onto the single 2.5" pipe coming out after the rear resonator, the tips arnt welded all the way around the 2.5" pipe, also it could be the air hitting the divider between the twin tips.
Hope that made sence?
Heard of anything like this Abba?

[Not_An_Abba_Fan]

It will be the fact that those two resonators have been removed. Nearly every allotec that has hi flow cats sound like that.

The original cats are up near the manifolds, when putting extractors and hi flow cats on, the engine pipes with the cats and resonators are removed and replaced with a hi flow unit with no resonators. Those resonators were put in from factory to take out the shitty sound.

[brods2151]

I dont get it you say that the cats are up near the manifold? Mine are just infront of my front door handles. Are you saying that i need to put a resonater on each of the pipes coming from the cats?