OK I just finished installing the UR HF cats. Took about 3hrs. I crankedthe nuts down good.

OK I start it up... W/windows down and listend for leaks. I didn't hear anything that sounded bad. At least like a hole in a exhaust.

First thing I realize is that yes it sounds deeper, but the car feels like a race car. I mean there is a thick vibration in the petal and shifter that was never there before. NOT a Noise vibration, but its the feel. Its not necessarily bad, but I want to make sure its normal for HF cats.

I think there is more power top end, but I wasn't thinking about that during the test drive.

Does anyone experience this vibration I am talking about? If its normal I am fine with it, but I want to make sure.

First thing that came to mind was that something crawled into the exhaust while the old HF cats were off. (I left them off and went to bed finished the install this morning.)

I have never been in a Z w/HF cats before.

BTW no CEL light after 10 miles I have a 04.5

 

I don't experience any additional vibration over stock. You must be contacting the body somewhere...

 

There is no rattle noise though?

 

If there is a vibration in the pedal, shifter or anywhere, there is contact with the exhaust and something else. Get under the car and look. It will only get worse. This is not normal.

Lou

 

What about the cat support bar? I tweaked it down pretty good. Maybe too good to where the rubber gromets are doing nothing??

 

Was I suppost to use OEM gaskets w/ the UR cats?

 

I originally anchored the HELIX cats to the frame...sounded and felt really, really bad. But it was only a temporary fix until I could anchor them to the OEM brace. Fixed it! Felt like stock again, but with a nice aggressive tone. I agree with the others... the underbody is making contact with the exhaust at some point.

Zquicksilver

 

Thank you all!!!

I found a point where the body was making contact with the HF-Cats.

Fixed it and its working great!!