DeLSoLRo

99 Civic Ex. I have a DC 4-1 one piece header with no cat/exhaust system. Cat got clogged/broken and stock muffler fell off.

I purchased a Yonaka 60mm exhaust system, and a "high-flow" Yonaka 2.5" catalytic converter which has yet to arrive.

I did not realize the size of the cat till after it shipped, basically im looking for feedback/knowledgeable advice.

From my research, the header outlet size is about 2.0". The cat in/outlet is 2.5" and the cat-back exhaust is about 2.36". I figure since the cat is the most restrictive part of the system the larger size should benefit flow.

I have a few questions about this setup.
1. Will this setup run fine?
2. Should I purchase a 2.25" cat instead?
3. Should I purchase a header with larger outlet?
4. If i keep the current setup, what should I expect a shop to charge to weld reducers/flanges from the header/cat/piping?

Thanks in advance for the reply's

DeLSoLRo

Bump

cvcrcr99

What is the car being used for? If DD, see below:

1. Yes
2. No
3. No
4. Why do you have shop doing this work? Get under the car and install it yourself. You shouldn't need reducers etc etc.

DeLSoLRo

Its my daily. Let me post pics of the items first and then you can answer that 4th question again.





From the looks of it, that catalytic converter is going to need some flanges to bolt up to the header/exhaust piping and a bung for an 02 sensor. Im pretty sure im going to need a reducer welded to the cat to be able to connect it to the downpipe (the whole 2" outlet to 2.5" inlet thing), but im not an exhaust system expert so i could be wrong.

DeLSoLRo

bump for more input