I'm running the Fioroni centax clutch, basicaly the exact same thing as the werks... I'm using 2 carbons & 2 teflon shoes, love it!!! It gives my S5 a ton of bottom end snap & they are super low maintence as well.
Mine went on with no problems... Didn't have to modify anything & yes it is a thinner flywheel vs the stock kyosho one, I just re-used the same flywheel collet.