L99 question (Headers back)
 

I am about to get some headers and high flow cats for my L99. I have a GMPP axle back right now that I planned on leaving along with the factory mid pipes. I was told the factory mid pipes arent restrictive but here is my question.

In the morning when I start my car and it is cold out I hear a slight rattling. What is this caused from? If this could ever be from those mid pipes I want to eliminate this problems at the same time I install my LT's. If I did this I will probably just buy a whole cat back system. I still can not find any solid video clips of Camaros with long tubes and a gmpp axle back.

Thank you for everyone's help.

I will be buying Dynatechs, Kooks, or Texas Speed headers. Havent decided yet.

Do all of these go around the steering shaft with out having to remove it?

The rattling could be a mulititude of things. It's hard to diagnose what it is without looking at it. I'd start by look at the axleback clamps. When the pipes are cold, it could be causing a exhaust leak which can sound like a rattle, then it goes away when the pipes heat up and expand. There should be no problem fitting your LT's to the OEM exhaust and plenty of people do this. Personally, I don't see the need to spend $800+ on a catback when you're replacing 2.5in tubing with 2.5in tubing. Some just like having a complete system and that's fine too. Replacing the resonator/H pipe section with a X pipe is a good weight savings and gives the exhaust a little different sound.

My TSP 304 headers did not require touching the steering shaft. Fit was perfect and installation was a breeze.

Check for pipes rubbing on the tunnel brace or could be the heat shields ratteling.

I found the video of your car. Are you happy with the sound of headers with the Gmpp catback? How much did the volume and tone change?

It sounds like metal rattling near the middle of the car. I just broke 6500 miles? I'll get it on a lift and look when I install the headers.

I had a rattle that was coming from the resonator. Apparently something came lose inside the resonator. Dealer was going to replace it but I just went with the x-pipe.

That's most likely the tunnel brace vibrating against the exhaust pipe.....add some washers to the bolts and that should kill that noise. If that aint it, it could be the resonator ... I think some have experienced with something breaking off in the resonator and rattling inside. Those are the only two I could think of.

You will probably find the culprit when you install the headers just bump the exhaust with your hand and try to make it rattle.

Yup. Like the others said it's gonna be really easy to find when it's up in the air.