Right, im getting confused. I want to get a sports cat and Im getting confused on bore sizes as I don't have a standard cat to hand to measure. The end of the mani is 2.5", so i will presume the bore size at the top of the cat will be either the same or a little smaller to fit inside. Can someone tell me if a 2" sports cat will fit. This may seem a daft question but for some reason Im under the impression that the cat pipe reduces in size as it gets to the cat. No doubt im completely wrong but need to make sure before I go ahead and buy this.

I don't want to spend hundreds on this. Ive found one that i can get welded in. Was going to take it to a guy I know, but want to make his life easy to keep the cost at rock bottom, so if I get the right size, its going to be a straight weld instead of having him build it up to 2.5" if I got the 2".

Edit: Just found out its 62mm. Why I thought it shrunk I will never know.

I think a 2 inch cat will close the system down too much. Restricting how fast the gases exit the exhaust. The standard cat size is 2 and a half inch.

You could fit a reducer pipe from the manifold to the cat if you wants 2 inch but IMO I think this would do more worse than good.

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