I did a search and did not come up with too much about lightened flywheels for the 4th generation. I'm planning ahead right now that my clutch will last another 6 months or so or hopefully another year until the Quaife LSD comes out. Then, I will put in the LSD as well as the centerforce dual friction clutch in, and a lightened flywheel while I am getting the transmission dropped. Is Muellen the only manufacturer of lightened flywheels? Does anybody else make flywheels such as Jun?

 

It was probably just a rebaged one though. It may be different from the brand you mentioned though. Either way it works great, the car revs up a bit quicker with it.