To begin with, the warranty isn't selective, it's the dealerships interpretation of the warranty that is selective.
It seems to me that the west coast dealerships are much more fair about it, right out of the whole. It just doesn't seem to be an issue with us near as much, out here.
The Magnusen Moss Warranty act spells it out that if they're denying the warranty due to modifications, that the modifications have to be a direct result of the failure.
If it's due to cosmetic issues such as chrome related......many of the dealerships have already honored the warranty and stood behind the product. I think if it came to legal action that the precedent has already been set by various other dealerships and backed by the Motor Company and that an individual dealership would be forced to honor it, at that point.
Let me conclude by adding this, my opnion and experience, that if you think Harley Davidson has a bad warranty policy then don't buy a Ford!