There are quite a few LSD (limited slip differential) options on the market for Alfa Romeo 4C, but Drexler LSD is the only clutch type on the market. This is the ultimate track oriented LSD. Why?
Mechanical, clutch type LSD's are the type of LSD's that are used in every serious race car from rally cars to F1 cars and the reason for that is their effect on handling. Due to their preset, constant locking rate and preload, the clutch type LSD's are more predictable to drive than gear type (Torsen) type LSD's. Clutch type LSD's also have adjustable preload, lock ratio and lock percentage which can be adjusted accordingly.

Our GMS spec's Drexler LSD for Alfa Romeo 4C is 1.5 (30/45) way LSD which means it locks 30% lock on acceleration which will greatly reduce the chance of inner wheel spin on tight corners and hairpins and 45% on deceleration which provides greatly improved stability during braking. This is a very good all around setup which shall suit most of the users. For those, looking for even more aggressive effect of the LSD the locking rate can be bumped up to 1.5 way (40/50). The preload is set to 52Nm, and it can be customized.
 
This is the ultimate LSD for serious track use. It's adjustable and predictable to drive. Unfortunately as with every high-end racing parts, the downside of clutch type LSD over torsen type LSD is its limited lifespan. While torsen type LSD's usually come with lifetime warranty and only require oil changes from time to time, the clutch type LSD's also require a rebuild (clutch pack replacement) from time to time, depending of the amount of time spend on the race tracks. This requires a removal of transmission which is an engine out job. On the other hand, if you are a serious tracker, you'll probably be looking into the TCT clutch replacement about the same time as the LSD clutch pack replacement, so both can be done at the same time. For majority of users we are confident that Wavetrac®, torsen type LSD will be better solution, due to it’s lower performance / maintenance costs.