Indeed they do! Both the SRT8 and R/T are available with a 6-speed manual with limited slip (part of the trac pack). It's also my understanding that the traction control will be able to be completely turned off, unlike reports I've read about some earlier cars.

I'm with the others here, I think the expense and effort to put in a V8 would be more than most would want to deal with. Maybe a nice small block chevy, like one of the LS series of engines would work nicely? That would be interesting to see. I saw that someone put a SBC motor from a C5 vette into an e36 M3 a few years ago. That car was crazy!

I think at the end of the day, the average crossfire owner is happy with the available OEM options. Either they like the coupe enough to buy one, or if they want more power they just go with an SRT6. The majority of people haven't gotten creative with the crossfire...yet.