Need help with Cat Converter

It's for 88 4.0L. I need one in a short notice and cheap, so local part stores (Napa, Autozone, Pep Boys) are the only option.

a. How do I know if it's a 2-way or 3-way? If it has air tube, does it automatically make it a 3-way? Box only said EPA Approved.

b. Can I get 2.5" converter and then downsize the exit pipe to 2.25" to improve gas flow (non-high-flow cat)?

Thanx...Eddie

Don't have any idea what 2-way or 3-way refers to. The direct fit cats I get from Summit Racing for the 88s come without an air tube, for whatever that's worth. They have a 2-1/2" input and an outlet pipe that's 2-1/2" at the cat body and then necks down to 2-1/4".

3-way filters out more toxic gases.

Thanx. I will go for 2.5" then.

Ask the people at the fawkin parts store to see one then youll know what it has and what sizit is. :looser:

Already did that. That's why I am asking the people on this forum. Box doesn't say anything. The people at parts store didn't have a clue what a 3-way converter was. To them it had 2 pipes, so they thought it was a 2-way!

OEM cat is 2.25". Downpipe is 2.5". Catback is 2.25".

Eddie