1999 Civic DX
Went through 25+ Threads didn't quite get what i was looking for.

Thought it was O2 sensors, so bought and installed the upstream+downstream and now i'm broke, P0420 CEL still shows after being cleared many times.
My timing is going to be re-done next week.
I can rev past 4,500 in neutral, but in any gear only 3,000.
At around 2,000 revs while driving i'll randomly lose power and feel like i'm cruising in neutral however i'm on the pedal.

With a stock y7 exhaust manifold, is it possible to gut out/unclog the cat. 'm aware it's illegal, but there aren't exhaust/emission rules here in my area that's so no worries there.

 

You need to get a new cat.

 

I'm not aware of any proven method, some gut the cat, some actually clean the cat with detergents, a big *** bucket and some water.
I'd say if your going to gut the cat, try cleaning it first, whats the worst that could happen?

 

But with a new cat, i'd need a new manifold/header and looking at my wallet...



True, cleaning is better than gutting first. How would I go about doing that? considering it'd be the whole manifold.

 

Why do you need those? It's not like your cat is permanently attached. They are replaceable. Unless they are uber cute. Then yea....

 

Whaa? I thought y7 exhaust manifolds and cats were welded together....
I'm becoming confuse on what cat you're referring to now.

 

Oh... It's Y7...

 

Y8 header with a used OEM cat

 

Well there's a guy in my area selling a Y7 stock manifold+cat (claimed not clogged) for $30, i'd try to ask him for $20 since it's been listed for sale for months but no buyers. Would I be better getting that?

 

Well, go check the condition on that and see how it is. If better than yours and not clogged, then hells yeah!