I have a '04 coupe, NA with 6spd manual. It is a fun little car, I am sure the SRT6 with another 100hp would be even more fun, although the auto might deminish your fun factor. Depends if you want to row your own or not . . . If the car is in good shape, when go for it. . . check over at the crossfire forum for further information. . . one other consideration . . . the '06 and up Mercedes Benz SLK55 AMG are getting down enough in price to think about one of those versus the SRT6 - MB made the SLK55 a bit longer and wider, so fits a larger guy (such as I) better, and you have 5.5 litre, 360HP NA V8, with 7 speed automatic, AND, retractable hardtop !! . . . I ended up getting a '06 SLK55 AMG, and WOW !!! It can definetly keep up with muscle cars (or better them), as well as modern muscle - and the SLK handles/stops !!
Cheers
Mark