Fidanza flywheels are popular because they are cheap. But, Like most aftermarket flywheels they are not made correctly....... Even on fidanza's website is says they add extra bolts to the flywheel insert because they need them :) RPS has found a much better way of making them then adding extra bolts that still warp. RPS has segmented the inserts so that they float instead of pull against themselfs. RPS also balances their flywheels and other aluminum flywheel manufacturers are not. RPS also installs locking steel threads for mounting the clutch plates, where others have only aluminum threads that easily pull out.
For more info and pics you can go to our web-site at specialtyz.com and click the flywheel pic under RPS Products :)