Where can I find the engine code so I can get the correct cat converter size?

Or how can I get te cat converter size for my car, esctunning has it as 2.25", 2.5", and 3.0", which one should I buy for my car?

 

If you haven't tried searching, do so please.

oh, and there are lots of knowledgeable people in here, but I don't think they can memorize or foresee what car all members have, so please, post a year/model... 1.8t? 2.8? y'know, at least the basics.... so everyone has somewhere to start from...

 

None of those are direct fit for OEM exhaust systems.

what make you think you need a new converter?

 

2.25", 2.5", and 3.0" pipe diameter size not catalist size ya gotta laugh aint you

 

People, bear with me, two months ago, I don't know shiz about car, but two months later, I learned a lot about car, but I still have a ton to learn, so bear with me, and help if you can. Thanks

so, 2.25", 2.5", and 3.0" pipe diameter size, how do you determine what pipe diamether size I need, or can I just use any, will it make any difference?

 

Because I got this engine code: P0421

 

What car are we talking about here, if we knew that we might be able to give you a more direct answer

 

that's a simple one p0421 is bank 1 catalyst ( that's the side where number one plug is on if its a V6 ) you cant make a mistake changing it because you can only buy the one for that side they are both different and include the front pipe as a single unit

 

I really appreciate all your reply, but I must admit that all your reply is useless to me some way or another.

So, are you saying bank one means the side on the driver's seat or the passenger?

 

I really need your guys help.

which size---2.25", 2.5", or 3.0" pipe diameter size is the correct pipe size for my car in the sig.