I can vouch for the SOS Sport Clutch. I have it and absolutely love it. The heavier PP took a little getting used at first, as the pedal feel is considerably lighter than stock. Like mentioned about the Exedy, it was very grabby at first but eventually smoothed out. At times it can be a little annoying during traffic, but couldn't be better during spirited/hard driving. Down shifting is a lot easier, and a lot more fun with the lighter flywheel. I'm using the 11lbs flywheel, I don't have any experience with the ultra lightweights. I've got about 6k miles on it so far with no clutch buzz at all.

 

You just may have sold me on the SoS for my next clutch.