Full exhaust was definitely a wise investment. Its not a HUGE jump in performance but worth it. I have the pypes lts and they are WAY more than i paid for. well worth it. the only problem i had with them is: on of the primaries rubs just barely on the steering shaft ubolt. i fixed this with a file and ground down the sides just a tad. small fix, easy to do.
with my setup, pypes lts, vrs p/r x, slp lm2s the car is DEF quieter at idle and cruising rpms. it comes alive when u get on it. my old setup( mac catback with catted x) was louder at idle and cruising.