Since there seems to be quite a bit of interest in what exactly is included here's a list of the entire range of components that's included within the newly released Cooper kit:
Cylinder Head, Air Filter, Cover Injection Tube, side & rear Emblem, and the Sport Exhaust. All the other components listed are just standard stock items that replace what comes off the car.
The quoted time for installation is 5 hours. Add that to the $2650 sticker price and you have around $3100 depending on your dealers hourly rate. As stated earlier the Cooper's horsepower jumps from 115hp to 126hp while peak power comes on earlier and is more readily available. The torque goes up 4lbft to 114 and it's peak is actually 4750rpm rather than the standard cars 4500rpm level. You can see the full chart here.
Interestingly the JCW sport exhaust is indeed the same sport exhaust that MINI has sold for the MC for the past 2 years. Not sure why MINI never advertised this before as I'm sure it would have sold better had they let that slip.
When I asked a MINI higher up about US availability I was told this is being released in very limited numbers and is already on back-order.