I seen that build too, way too much work for me lol. plus i need my backseat :P. I grounded my amp to the right strut tower bolt, works great.

I am not worried about squeeks from my sound system, I am worried about the squeek/clunk from the left rear. Idk if its the exhaust or what but its annoying as hell when i have a lot of torque from a standstill.