brought the high flow cat I bought up to the exhaust shop I bought the universal 3in/3out he says its too long and I need a 2.5 , anyone help me purchase the correct cat for the truck .

I bought one for my ram and it was a big difference in sound and power . what do you guys recommend ?

this is the one I bought

 

I've haven't changed my cat, but I do believe it is in fact a 2.5". Sorry I can't help you more.

 

thinking ofthis cat

 

I guess it would make sense to compare it to the dimensions of the oem cat. I'm not sure if those are floating around here or not.