The slightly higher cost of the Exedy unit is offset by the fact that you don't have to pay that UPS charge to return the old one. AEM is the sole Distributor of Exedy flywheels, however, they are imported by Daiken corp out of Detroit. Another side note is that the JUN chrome-moly flywheels are actually made by Exedy so they are the same unit. Pricing is identical. Power was great although I suspect some of the gain is from the Type R trans installed.
Some gain is from weight being restored.
As I have written before, the combination of such a light flywheel with an aluminum crank pulley causes loss of low end torque. Although slightly heavier than the aluminum Clutchmasters unit, it is also slightly stronger although the chances of breaking either unit is minuscule unless you're running 500 HP at the wheels or something. Also, it is much stronger and safer to go with either of these flywheels than to shave your stock one. I highly recommend that people perform this mod when they change their clutch. I purchased my alluminum flywheel from Clutchmasters at the same time as my Stage II clutch.