jhanson9 answer!
I haven't gotten the kit installed yet. With all the information from Corky (the mfr.), I do not expect to need new halfshafts or a clutch plate. I do plan on looking into the ACT clutch and possibly a flywheel. Wheel hop will be present in most front-wheel drive cars, regardless of boost. You can partially correct this issue with motor mounts, something else I am looking into.
I paid $3000 shipping included for the kit. Flyin Miata has taken over production of this kit for an unspecified price. I will be running between 6 to 7 psi (another reason why halfshafts, etc. are unnecessary). If you check the dyno charts at Flyin Miata's website, this kit will outperform the Calloway Kit on the MAZDASPEED Protege by a wide margin with the proper exhaust setup.
Its a shame that you are trading away your P5, especially if its on the wheel hop issue alone. If anything, wheel hop and torque steer will be far worse on the MSP you're going to buy. The latest issues of Car and Driver and Motor Trend confirm that much from test drives. One tester was quoted to say "I'd just like to have the turbo motor in the MP3" due to handling issues.
Oh almost forgot, I expect the install to cost around $500.
