What size inlet/outlet cat should I get? I want to put a high flow cat and a new muffler on my car. I checked the size of the downpipe to the cat and the outlet and they are both different. The inlet measures 3" and the outlet 2.25". I'm thinking 3" in and out, then reduce it to 2.25 after that. What do you guys think? Also, do these cars have an air tube on the cat? I forgot to look when I was under the car.

This is the one I am looking at.
Magnaflow 94309 Magnaflow Performance High-Flow Catalytic Converters

Thanks.

 

are you measuring the inside diameter on female one end and outside on the manly end. how long is the stock one

 

You can get them much cheaper on eBay, and that is the most common size used on the v6, just most upgrade the exhaust as well. Why even use a high flow cat on stock exhaust?

 

I was just measuring the outside diameter with my calipers of the pipe coming from the y-pipe to the cat, and then the outlet on the cat. It looks like the male end going into the cat reduces slightly, but not by much. I don't have it off the car so I can't check the inside diameter. The cat measures about 18" long.

I'm not planning on buying it from Jeg's, they just had a better description on there. I can get a new one on Amazon for $92 shipped. And it's not going on a stock exhaust, I plan on getting a new Magnaflow muffler and having a local shop replace the rest of the pipe from the cat to muffler.

 

I would go 3 in in and out, then buy a cat-back, instead of just replacing the muffler. If you do a 3 in. Cat-back then no reduction required, else do at least a 2.5 in system...

 

depending on your state law you may want to replace it with one the same size and type. agree with liberty if your going with 3 in exhaust then go witht the 3 in.