The 2 main options for a tuned S3 are the RTS dual friction and the Helix. I had an RTS dmf version fitted to my S3 at Awesome. They need a lot of running in up to 1000 miles of town driving and can be juddery to begin with but the benefit is the clutch pedal feels standard.
Less running in with the Helix but the clutch pedal is firmer than standard. If I had a Helix, I’d have it fitted at AKS due to their excellent customer service and relationship with the Helix factory.
In any case but especially with the Helix, it is essential to fit the “press clutch to start” delete harness to avoid wear on the crank thrust bearings.
We have a Sachs in a TSI engined TT. Less effort than the Helix and very smooth. Not quite as high torque capabilities though.
I had my clutch and DMF replaced in November and went for the RTS DMF combo. As mentioned above the first 30-50 miles were horrible but after that no issues with judder or how the pedal felt. I’ve taken it fairly steady as RTS recommend 750-1000 mile of town driving to bed in. I’ve done 850 now and still have the slightest slip on occasion so still plan on doing a few more hundred miles before giving it full boost through the gears. I don’t have one to compare to but I’m very happy with it so far.