The US Cup car and the European 964 RS are the same car other than the safety equipment mandated by US DOT, like door beams, air bags yada yada. They are nothing like the RSA or US C2's. Much lighter, way more raw and amazing. I've driven both a US Cup that had not been converted and a Euro RS and both felt the same. I owned two RSA's and although they were great cars in their own right, they were no where near as amazing as the RS or US Cup. Simply brilliant cars!
As good as these 964 specials are, the 996 GT3 is just that much better....and you can have them at bargain prices, right now.....but I digress