On ronayers.com if you go look at the michelin pilot powers it states:

PILOT POWER 190/50ZR17 REAR .......................$147.95
PILOT POWER 190/50ZR17 REAR 2004 R1 OEM SPECIFIC ................$117.16

what the hell is the difference in the tires.

no one knows?

I have you called and asked them??? Also, OEM tires are normally a little harder compound to have a longer shelf life in order to last while sitting in the showroom. Think more sport touring tire than race tire.