hok-16823hkr catback system vs. hok-16820hkr hooker catback part numbers on summitracing.com one is 275 on is 295. $20 difference, they both seem to be the same system, whats the differnce between them?

 

I think the difference is the size of the pipe that hooks up to the cat. The 16283 is what I got and I'm running a 3" cat. The 16283 comes with a 2.5" test pipe(i dont know why it wasn't 3") if you dont use a cat.

I think 16280 is for a smaller cat.