What's the difference between 2'5 100cpsi cat & a 3' 100cpsi cat?

Running flash tune & 2'5 sports exhaust from the cat back.. im assuming 2'5 would be the wiser idea due to having a 2'5 exhaust?..3' would just lose compression? thx

with the cat its just the size, im not to sure which is better suited for the xr6.
2.5' inch zorst is all you need, you'll only need a 3' if your planing on pushing a lot more power out of it. you won't lose compression with a 3 inch, you shouldn't lose any-power, you will however get more of a drone.
im running a 2,5' xforce zorst and ive had no issues with it, it sounds great and is just about as quite as standard when cruising.

Yeah got my venom 2"5 high flow sent over. 180$