Srt-4's are extremely torquey, can make about 300whp for a very small investment, have been shown to handle up to 450whp on the stock block reliably, and actually come manual. Do you have any idea how much a custom six speed transmission is going to cost? You can't just "do" these things by yourself, these aren't old american carburated cars where you drink three beers and are done swapping an entire motor and tranny if three hours. The electronics involved with modern german cars is baffling even to those who make them. If it was easy to do an engine swap, someone would have done it by now. It's taken hddp and lantana a long time to get their done and has probably cost more than they would want to tell us (or will end up doing so).

Point is, the best way to buy a fast crossfire is to buy an srt6. Second best way is to swap in an srt6 engine because the motor has proven to handle more than 400whp in other applications and was made for this car.

But if best of luck getting it done, it would be one bad as s ride if you did it.