It's not that they don't sound as good they're just different. I never heard a Fox that sounded like my '68 Fastback w/ a '70 351 Cleveland but they're all good, just different
Anyway, not bad, now get some long tubes on there!
I hope you are considering the bottom end of your motor and fuel delivery. The general consensus is our motors are only good for 450hp, higher than that you should consider forged internals. You'll also need to think about a KB Boost A Pump...
Brand new car vs. 5th year body style. A lot of people have been waiting for the Challenger. I think it appeals to a very limited market. Once that crowd has their cars sales will probably fall off. Not to mention Chrysler will do anything to move a car these days.