I took 'em off - all of it - mid muffler and resonators and had the exhaust shop add a little straight pipe in (no pup cats I have an 08) - why? Because I wanted a 2.5" "catback" but didn't want to pay stupid money for one. I pieced it together myself (what I've done w/ most cars/trucks) - and had an exhaust shop do the rest.
Get rid of all of it....the resonators I'm sure flow "OK" but I bet straight pipe flows better....
'08 GT sport/premium, tints 20/35, 18" TSW nogaros w/ bridgestone blizzak winter, 19" sport oem w/ hankook evo summer, Philips crystalvision bulbs, debadged, Vararam OTR, JBA 1-3/4" LT's, ported TB, MF axlebacks, MF X-pipe, DBA-powerslot brakes, russel SS lines, hawk ceramic pads, GXP shocks/struts, lovells poly strut mounts, Slowhawk Tuned 344/356
Gone -'04 GTO A4 2.5" custom exhaust, sweet thunder muffs, H pipe, Z06 heads, Baer brake it, 20% tints, torrid red, AEM brute force intake, tuned