I recently installed a YCW (dry) carbon fiber driveshaft on my 1M, from teammfactory.com. I weighed the driveshaft on my super accurate bathroom scale @ 12lbs. Picking it up, you immediately notice most of the weight is in the rear CV joint (empty ice cream box feeling).
I've only had the car for a month, but my first impression is more direct throttle input (tires rip loose easier). I'd read reviews from E9x M3 owners who claimed a reduction in NVH, and I agree. The single piece shaft is definitely smoother with less noise and more feel.
Make sure you check the heat shield clearance. I was in a small hurry and didn't notice it was just barely rubbing in the rear (only under deflection) until the next day. There wasn't any damage, just removed a layer of paint from the metal end of the shaft. I used the backend of a plastic screwdriver handle to clearance the shield (circled in orange, below). The flanged connection to the guibo is also machined in such a way that you can just barely get a wrench on the bolt head. In any case, for roughly the same price as an OEM shaft, you can make your 1M a little more exotic and put some carbon where it counts.
I also installed a 128i performance shift lever (after removing the too short Dinan lever) and it is sublime, p/n 25117542200. The knob is noticeably higher, but feels perfect to me. 1-2 and 2-3 shifts both feel how they should've from factory (timing wise). I'm definitely not feeling the stutter into 3rd, but I also changed trans and diff fluid, YMMV.
