Bottomline is.......speed costs. Look at what drag racers pay to get that tenth of a second faster time.
And where are you going to use the extra horsepower?.....street racing?....bad idea...Bring it to the track if you have something to prove.
Who cares how fast your Challenger is, because you have to slow down anyway if you want to give Mustang and Chevy owners a chance to see your Challenger.
Enjoy whatever kind of Challenger you get.......even if you don't get the best one...SRT8 (just kidding).