For roughly $5 grand and your own sweat labor, you can get all the SRT6 drivetrain components and electronics to do a transplant. Other than that, would be very costly and time consuming to boost the NA drivetrain.

You need engine, transmission, drive shaft, rearend and axle shafts, matching electronics, at least ECU, TCU, SKREEM, key transponder, instrument cluster, possibly body control module. Also would need the SRT6 secondary air pump and brackets, air to water heat exchanged and pump, and some wiring harness changes. Probably couple other odds and ends.

An 04 presents another challenge, the ABS system and harness is different than the 05 models. So there is something that has to be addressed there as well.

Then you would also want to upgrade the brakes.

If the Crossfire being converted is a manual, then cost just went up more.