with or w/o cats? its gonna be loud as hell either way! i went with cats to avoid being too raspy.
some advice:
1. get a can of pb blaster, and use it moderately on the drivers side manifold studs. try to get your hands on a stud puller ahead of time, it will save you a great deal of time and stress. if you cant obtain one, soak the studs really good with pb blaster top to bottom, let it sit for 10-15 minutes, then use the "two-nut" method to remove the studs.
2. if possible try to let the car be as cool as possible before starting the job. getting the forward o2 sensors disconnected sucks if your tranny is hot, b/c it stays hot for quite a while and it was a pita for me.
3. you will need 15mm socket, ratchet, extention(s), and
universal! prefferably 3/8" drive, and if i remember correctly, a deep well is "too" deep on the passenger side nuts for some reason.
it may give you a hard time, but overall its not too bad. good luck! you'll love the finished product
the above mentioned drivers side manifold studs finally removed!
the finished product