hey, i got my dual exhaust with dual outs, so like quads, last spring. i had the guy at the body shop cut out the shape, roughly like the other side, and then when i got home i filed it down really smooth, and even. since my car is black i just took some black permanent marker and colored on the inside, you can't even tell the difference
I am redoing my car as we speak, Yesterday we ran duel exhaust right through the bumper. we filled in the factory Z-24 spot with rivited sheet metal and then smoothed it in with Dura Glass. Can't even see the rivets or lines. I hope it don't melt the Rubber. we left a 1/8 of a inch around the pipe. and only the very edge of the tip sticks out.