would a buddy club spec2 and a kteller 2.5 inch cat back bolt up to the same cat or will they each require a cat seeing as one is 2.36 inches and the other is 2.5? They will be used at diferent tracks depending on the noise limit.

 

If the flanges mate properly they should bolt up, there isnt a whole lot of difference between 2.36 and 2.5. And if your running a cat I cant see noise being an issue.