Civic EG

well so i recently got a new eg8 and it had this terrible exhaust rattle so i thought it would be the heat sheild because when i taped on it with the handle of my screw driver it would make the noise.So i went under the car remove the heat sheild which is between the cars body and the cat. only had 2 bolts left holding it in , so i took it off. started up the car, still rattled but kinda less not that big of a diffrance. So i thouhgt i should take off the heatsheild located on the cat, so 5 mins latter and a lil prying i got it off, started up, still rattled. i went underneath the car hit the cat with the screwdriver and guess what it was cat that was rattling all along. so i thouhgt my cat was probably cloged/ dead. problem here is should i replace is now also the previous owner who had a catback on it cut off the flanges and welded it on. the piping is brand new from the cat back would i have to cut it, weld a flange on both sides then install a new cat ?

Well most likely some of the cat internal stuff got disloged and is rattling inside....but yea your best bet for eease if your going to keep this car for awhile....is take it off and do what you are saying but if you go to advanced or monroe you can get one of those V8 flanges for their exhaust the one with 3 holes and one big hole like a triangular peice...this is what a buddy of mine did to his ek when he changed manifolds.....

but yea that would be your best bet and just get a o.e. one or something like that


Or (this is bad for environment or illegal ) but you can hollow out your cat which would get rid of that rattle but would give ytou a much different exhaust tone...

it will give it more of a rhaspy/ricey noise, especially with an aftermarket catback.

If you can weld then you could buy the flanges and DIY, but it would be a hell of a lot faster and easier to take it to a shop, and they will most likely have a warranty

just took it for a drive today, got it insured. when i drove it with the guy who i bought it off it ran good. now i drove it, pedal to the ground engine revving good but the car isnt moving very fast. i know its a d-series but dam can a car be that bad with a clogged cat. i removed the heat sheild which i think may have knocked some shit around in there and may have abstructed the flow. i also degressed the engine and have thouhgts water may be causing this. also added knew plugs so i dont know whats wrong.
a million things are running threw my head right now, not shure what is causing this. fingers crossed its the cat

time to replace it, my cat on my Grand am(RIP) did the same damn thing.

got the cat replaced at work today , it rips now. gained all the power back and got rid of the rattle.

good deal
Did you get a core on your old oem cat? They're usually worth about $50 or $75 because of the metal inside of them.