I have 03 coupe, I used the pre-existing ground on the metal "bump" between the trunk & the back of the backseat. if you drop your backseats and lift up the carpet that hangs over trunk, you'll see it right there, huge ass bolt, I just added my ground distr. block to that and have all my grounds attached to that.
there's also another pre-existing one on the left of the trunk, right above the plastic panel next to the plastic door to change your tail lights, pull back carpet panel and you'll see it but I think this one is the main trunk ground or something because there's like 7 things grounded, that's why I used to the other one.
