i know what you mean about slump. Got the g8 to where i wanted. Always had headers on the list, but the cost at this point isn't worth the investment for a 10 year old car. After moving and with 3 kids, it's hard to stay engaged. But, like you I now focus on detailing. It's a way to stay in tune and get some return on my labor.
2009.5 G8GT Premium OnyxRed Interior
corsa catback, vararam intake, cortex tune
custom audio, sharksfin, HIDs, LED Fogs, 20" MRR GT1's