Originally Posted by nemiro

If you're wanting more gears, then another potential option will be the 722.9 7G transmission. They have been slow on the uptake in the performance world, and add certain other complexities, but the MB world seems to be happy with them, and the extra gears may give you that closer ratio setup you probably would want. Getting it into the car would involve fairly little, in terms of fabrication: New driveshaft and likely some mods to the trans mount. The real trick will be in the electronics. Not sure if Andrew handles the integrated TCU of the 722.9, but there are people who do.

And you probably already know that Dave on SLKWorld is planning a 722.9 behind his 5.0 M113 in a R170.

On a side note, I planned on going the 722.9 route myself, until Andrew worked his magic, and made the 722.6 perform better than the factory ever did in these cars - by a long shot.