Not sure why it isn't showing up above but here's a bit more info on explaining "What it does..." from Rick. He has worked on some very high power cars and have had a similar brace for the 335 for quite some time I believe.
"Well, my initial driving impression of a s/c E9X M3 left me noticing a large deficit of proper power transfer to the rear tires and excessive chatter/hop from launch on the right surfaces, most notably a certain amount of instability/odd behavior during tire spin. There wasn't a sense of which way the car was going to go during aggressive wheelspin and high rpm DCT upshifts felt very "twitchy",if not a little dangerous. Further inspection revealed that the front two bushings matched the same poor design as the N54 cars and were damaged to a greater extent. Most importantly it shares the same terrible 3 point mounting strategy, which is the birthplace of wheel hop,albeit the upper rear bushing seemed to be stiffer than the N54's mount. Another thing that struck me as horrifically insufficient for higher output S65's was the actual LSD unit's design itself, the short/long axle shaft/axle cup spline design and the fact that the passenger side rear wheel can only receive a portion of the power at best leaves me in a position to highly recommend doing an OS giken conversion if boosting your S65 or building a stroker/etc. The factory unit is set to fail under extreme loads, not to mention power transfer is undesirable. Regardless of what lsd unit one runs power and the fact that the differential unit can twist/bang around once shock is applied will lead to only one thing; breakage will occur despite the stronger components utilized in the M cars. The theory and design of this variant are exactly the same as the N54 design, although the differences in diff covers,subframe design,etc led the actual solution looking quite different...but it's job is exactly the same. As a sidenote, I have been using OS giken with Supras for many years, so I can do the OS diff installs if need be as well as the supporting modifications/machining required to do so. OS converts the diff assembly to a stronger and much more stable equal length spline shaft/clutch type lsd unit that mirrors units they have been very successful with in preceding years. It's my first choice in clutch type lsd's. highly recommended in boosted/high output apps. Favorable results/added stability were gained running an oem lsd, much more than I expected. It really tightened up the back end of the car, I'm going to let LM get a full impression of the differences in the car because of his seat time preceding the changes eclipses the short test drive I had beforehand.I'll wait on his input before releasing officially, only because i want to ensure perfection."
2011 Space Grey E92 M3 Competition
Missing My AA Gen 2 Level 3 Supercharger 586whp 398wtq SAE
ACM Test Pipes . BPM Tune . Defiv Rear Diff Brace . 19" Black ZCP Wheels . Mode Carbon Front Lip & Rear Spoiler . Gintani CF Side & Rear Skirts . CF IND M5 Mirrors, Grilles & Vents . LightModz Headlights . M Perf Wheel