i have a 00 civic si that i have had for about 8 months. it is still a work in progress and funds are tight so its slow going. when i got the car the guy had some exhaust mods done. for some strange reason there was a rattle coming from the exhaust. i think it was between the header and catalytic converter(which was factory). i replaced the cat with a high flow and the rattle went away for awhile. recently it has returned with a vengeance. everything is tight and snug. i cant figure out what it is. anyone else have this problem and if so how to fix?

 

heat shield?
header to lower tie bar contact?

 

there is no more heat sheild. its gone so i know thats not it. have to check the other one.

 

Might be a cracked/bad weld in the exhaust manifold.

 

i know this sounds silly but when i did the motor on my dodge pickup i accidentally dropped a bolt in the exhaust wich went un noticed for months one day it decided to make a lil noise and it took months to figure out what i had done. anything that can happen will happen, good luck

 

i had rattling sound from my new exhaust, turned out the support was loosing up from viberation

 

i know what u mean man, just put on an aftermarket header on my 98 civic and i hear vibes and rattles sometimes, dont know what it is yet if i figure it out tho ill post it