Super40,
There are choices and they will mostly depend on your wallet size.
The Audi boxes are great because they are really cheap. Usually $150 to $300 range. As long as you keep the horsepower around 400 and the torque near 360 you should be fine with this choice. Higher horsepower will require the ZF box. It doesn't shift as smoothly but it will take much more HP and torque. This option is costly at near $9,000.
The G50 box from a Porsche 911 is another choice. It to is pricey as a rebuilt unit will cost around $2,500 at the cheapest.
Which ever way yo go the RF can be fitted with any of these.
Hersh
