Fonsi Nieto's
GSX-R1000
World Superbike
Often considered to be the premier homologation race series, WSB rules differ from the AMA most notably in the allowable engine modifications.
It's been argued that these mods make it extremely difficult for privateer teams to compete against the factory backed front runners, but countering that notion is the fact that we see much closer racing in the WSB series than the AMA.
A WSB machine costs just slightly more than an AMA bike based on the added costs of extra engine mods and the R&D to perfect them. $125,000 should get you a competitive ride-just don't fall off.
Exhaust
The entire exhaust system can be replaced, but the WSB bikes get an extra two decibel (107 dB) noise allowance over the AMA.
Frame/Swingarm
The same rules apply to the frame and swingarm as in the AMA, and in both series there must be a VIN visible on the headstock.
Nieto's bike sports a hefty aftermarket swingarm similar to Spies' bike. We can expect these to be factory Suzuki parts.
Wheels
Under Article 2.3.5.2, wheels may be replaced and associated parts may be altered or replaced from those fitted to the homologated motorcycle. Similar to the AMA, carbon fiber and carbon composite wheels aren't allowed unless the manufacturer has equipped the homologated production model with this type of wheel (none do).
Engine
Ducati ruled the Superbike class throughout the nineties, but that was largely against 750cc inline four cylinder bikes. Recent rule changes have allowed the 1000cc inline fours to get back to the front of the grid, but the playing field is still questionable.
Inline triples and four cylinder bikes have a capacity cap at 1000cc while twin cylinder bikes can go up to 1200cc. The interesting bit is that the twins must run a restrictor plate in the airbox. But, unlike the AMA, the airbox may be altered or replaced from those fitted to the homologated Motorcycle.
Otherwise, permitted engine mods are largely the same as the AMA, except that WSB can change all transmission and gearbox components.
Also, polishing and lightening of all engine parts is permitted.
Forks
Similar to the AMA's regulations, the entire front end can be changed. Every bike on the grid sports some type of aftermarket suspension, but in WSB we see an even broader scope of manufacturers. Where the AMA's top teams tend to use what the factory supports them with, WSB teams venture out to brands such as Marzocchi and WP.
Brakes
Brembo is again the most common provider of braking components, but we also see more elite spec factory items from companies such as Nissin.