I know I'm comparing apples and oranges, but the first modifications I competed back in 2007 with my 06 Charger was Mopar LT's, highflows, custom Magnaflow. My base stock dyno put down 296 rwhp, after just those bolt-on mods, 323 rwhp. Considering it's a 4,300 lbs. vehicle, with stock tune at that point I was pretty impressed.

Rob does offer highflows as an option, and I'm looking for a complete system (likely next spring). So with these headers currently under R&D, and down pipes, this looks pretty good as a combo setup.