I used the existing chin spoiler for mounting & fitment purposes. This will be what I use to make a mold from. It's actually one piece lip - diffuser. The pocess was foam + bondo + carbon. I used carbon because I had About 3 yards left over from another project so it was technically free.

I haven't done much research or put much though into the exhaust area yet as it will be a slow work in progress.

Thanks!