well the reason i am doing the exhaust is that it didnt pass smog. running super rich, so much so i could smell it pulling into the shop. i knew it wasnt going to pass. but it was the last day for registration so i tried just for kicks. no pass, so i just paid the registration and brought it home. i fixed the rich problem (mostly just a bad TPS) and bought a new muffler (old one is rusted through) and a new CA legal cat knowing that the rich mixture no doubt clogged the old cat. when the smog guy ran the test he said my cat needs to be replaced, and that even if it burned clean the numbers are not current. i hate CARB. the only CA legal cat available for an 89 XJ has 2.25 inlet and outlet. how you are getting away with a 2.5 on a renix i would really like to know. my new muffler has 2.25 inlet 2.5 out, so i need to get a new tail section aswell since the old one is 2.25 and totally rusted to heck. i see Rusty's sells a mandrel bent 2.5 tail section, and will most likely go with that. for now i will just use the stock down pipe i guess, and see about making a mandrel bent one later.