i got my prochamber at rpm outlet ( http://www.rpmoutlet.com/mach1maccat.htm#1 )....the prochamber will be a lot louder w/o the cats, but i got mine w/ them to pass inspection
if you want all of the performance and sound, and still want to pass emissions testing....i'd get the prochamber w/ cats....then buy the offroad legs for another 90$....the switch shouldn't take long before and after inspections