k so i think i've posted this before, but anyways. i bought a 2.5 catted downpipe from zzp. at cold starts there is a in godly rattling noise. first i thought maybe it was one of the baffles in the muffler. but i looked under the car to kinda point out the noise. all i can hear is it coming from the downpipe, where it connects to the header. maybe its the heat shield but i dought it. i remember some one saying metal could of gotten in there. i have GM wheel hop kit installed so i have stronger mounts. i'm wondering if this is one of those things that breaks and you have to send it back to zzp or what?

 

when i get home im going to take off the heat shield and see if it still makes that noise in the morning when goto work. i just read that some people had to adjust the heat shield or just remove it cause it was making contact with the downpipe. or the wings on the cat is making contact, making it rub. ill check it out once again this weekend

 

heat shields are becoming a common issue on the new zzp downpipes. check that out bc i also thought it was a baffle or bad cat.

 

the wierd thing is, i drove it with out the shield and it still makes a rattling sound. but i cant figure where its coming from casue im in the car driving.

 

i have same issue... but mines catless.

 

Sounds kinda dumb but are you sure your bolts are all tight? Cuz ive had that happen before where a bolt came loose and the washer was tapping the flange of he DP.

 

ok i took the heat shield off and thats what was causing the cold start sound. after that i went for a drive and still have the rattling noise coming at low rpms or just starting out. i took a look at it today and noticed the cat is rubbing on the heat shield. so now what? i tried to loosent the bolts and moving it a little and nothing...is this considered to be a return for not setting right?

 

bump

 

was emailing zzp and they are sending me a new pipe cause this one was not fitting.
thanks ZZP!!!!

 

Mine has been making a loud rattling noise at startup too. It sounds awful but it goes away when the car warms up. I'm running the zzp 2.5 mid length header/dp with cat for over a year now.