Will a 2.5in cat flange bolt directly to a 2.25in exhaust? I was checking to see if it's just the inner diamter that changes on sizing and not the bolt spacing, to make sure my 2.5in cat will bolt to my exhaust.

 

If you're referring to the 3 bolt flange, then most are universally sized regardless of the inner diameter. In other words, as you stated, it is only the size of the inner opening that changes, not the flange itself.

 

thats what I was thinking, thanks for the info.