Only on the forum for several months with my 08 GXP, but I read a lot about owners having a lot of trouble with their GXP tunes. Also read (perhaps the Ghost?) an older post that said engine life is 50% of normal with a tune. That said what is the "on the road" performance increase with the GMPP tune? Not too concerned with the more abstract dyno readings and PSI boost, just what is the "seats of the pants" feel, or 0-60 times, with and without GMPP Tune? (Would not consider a Trifecta tune). Or is it better just to do a few suspension mods for a little better handling (can't complain about stock handling though) and skip the tunes all together?