Its the giving season right? I encourage everyone to share information instead of keeping good info secret, this helps progress the platform. I could of very well kept this to myself and gone faster and no one would of been the wiser. Happy Holidays from BMWJunkie! The Idea: I have been working on David Rooney's 135i DCT swap for awhile now. I am very familiar with the look of and weight of the n54 DCT flywheel. While reading about a clutch upgrade on a f80/82 I noticed a picture of the flywheel in the m3/m4 and it looked much different and much lighter. I was curious and used realoem to inspect weights of the two. The difference was huge. The m4 part rang in at 8.1kg and the stock 335is unit was a whopping 12.92kg! I verified they both used the same bolts, same bolt pattern, thread pitch, and same clutch pack. On paper everything looked great. Located a used m4 dct flywheel from a junk yard and the project was on. The Swap: When the m4 unit arrived I could immediately tell it was a much lighter unit. I verified the splines on the clutch pack were the same and test fitted it onto the crank of a n54 I happened to have in the garage. Everything looked as expected. I pulled the trans out of my 335is and removed the DCT flywheel. The side by side shot says it all. The 335is flywheel is a typical bmw dual mass flywheel and the m4 unit while still listed as a dual mass did not have any noticeable play in it or even look like it was dual mass. It could be dampened internally but I could not be certain. As you can see in the photos the weight difference huge 10.5lbs between the two. The flywheel bolted right up. I used new flywheel bolts and torqued to the m4 specifications. The two cars share the same bolts. The Results: I took before and after free revving videos at roughly the same operating temp and the difference is noticeable. The car felt quicker after the upgrade, no more or less than expected. Worth the 300 dollars to me. I am hoping it will help my launches at the drag strip because I've been leaving too hard with the stock flywheel and 5k launch. I am also hoping this is easier on the rest of my driveline.