07whiteGXP

I installed my used Hogan downpipe last night and now I hear a very annoying sound under WOT, the sound resembles an exhaust leak. I replaced the gasket where the dp meets the resonator with an advanced auto parts gasket, but did not replace the manifold gasket. I put ultra copper RTV on both ends of the downpipe and on the resonator.

What is the probability that the sound I'm hearing is a result of not replacing the manifold gasket or that the downpipe has a pin size hole or that the flex tubing is bad?

While driving under normal throttle the sound is great, as soon as I go WOT is when I hear the sound.

Thanks for any input.

Vectus

iTrader: (1)

I didnt have this issuse when i did mine, i also bought mine used. I replaced the mani gasket and just had it welded to the res.

DavidGXP

iTrader: (14)

It's the flex pipe. Mine does this too.. Nature of the beast

07whiteGXP

Oh man, say it isn't so. I don't know if I'm prepared to live with this. Is there anything that can to done with the flex pipe to try and reduce the noise? Or has anyone brought this issue up with Hogan?

Thanks

DavidGXP

iTrader: (14)

Dam.. I miss read your title and thought you had headers installed.
With just a dowpipe you should not have any leaks, so no.. this is not normal. Replace the manifold to downpipe gasket.

07whiteGXP

I'm going to get the manifold and resonator gasket from dealer on Monday, and I am really hoping that takes care of the noise.

Vectus

iTrader: (1)

Davids right, idk if the dealer one will do it Call Hogan and/or order from his site. Give the guy who provided a great product some business while your at it

07whiteGXP

Vectus - You make an excellent point, I will do that.

Thanks

07whiteGXP

Well Hogan says it is not an exhaust leak and that the noise is the sound of unrestricted exhaust flow.

Their recommendation is to wrap the pipe. What is anyone using for exhaust wrap? Is 15ft enough to wrap the whole catless downpipe? Also is once around enough, or would it be beneficial to wrap it twice. My main concern at this point is not the heat, but to provide a bit of sound deadening.

Thanks

evil 5.3

is it a whistle you here

07whiteGXP

Kinda, its like a higher pitch whistle. Sounds like you put a stick in a house fan on the blade while it was spinning, but higher pitched...If that makes sense.

Vectus

iTrader: (1)

I'd still get the mani gasket to put in if you hadnt done so. That Might fix your problem, not trying to question Hogan but if you fail to explain that you hadnt done so then i can see why he might feel that could be the issue.

07whiteGXP

Placed my order for both gaskets a few hours ago.

After researching more it seems many other people hear the same noise and after wrapping the pipe it provides a little bit of relief from the sound.

I will update once I get the gaskets and wrap the pipe.

Thanks.

Brian396

iTrader: (3)

Did you get the DP with the Interlock flex? When I ordered mine I was told that the standard flex coupler would whistle.

07whiteGXP

I purchased the pipe used so I don't know, my guess would be no. I wish I would have known.

Thanks

1BAD06MCSS

David, did you buy the new set of headers or buy a old set? I have mine and want to know if they will make this noise when I put them on.