Great idea - I am still torn whether to plug the exhaust cutouts or build something from ABS. I really like some of the rear diffusers available for other cars, but will clearly need to build something myself for the Challenger if I want to go that route.That looks awesome! As for the rear facia, you could get a second one and cut some of the center out of that one, square cut the original exhaust holes, and bond it all back together with panel bond adhesive (it's made to do repairs on bumpers). Once you get it all bonded together, you can smooth out the grain and paint it to match your car. Sounds like a lot of work, but you could probably do it yourself over a weekend and a few beers. Good luck!