Here's some ideas to be concidered for TT2:
Motorcycle Manufacturers have a pattern, MOST bikes, at least Sportsbikes, have this tendency, each bike model lasts 3 years before it's updated. Allow each manufacturer to update their bike before taking the game out.
Yamaha: R1((Updated))
R6 ((Should be Updated after 08 model))
Kawasaki:ZX-14((Unknown))
ZX-10R((Should be Updated after 08 model))
ZX-6R((Updated))
Suzuki: GSX-R1300((Will be updated for 08))
GSX-R1000((Updated))
GSX-R600/750((Should be updated after 08 Model))
Honda: CBR-1000RR((Should Be Updated after 07 Model))
CBR-600RR((Updated))
It would be nice if PD allowed companies to update their bikes, to avoid the situation that happened with TT, the game came out, and shortly after, Kawasaki updated it's 6R and 10R and released the 14, Suzuki updated the 600/750. So now you ran older bikes.
Also, include classic sportbikes, Ducati's 996 and 916, Suzuki's GSX-R1000((The one with the headlight shaped like Superman, I think it was 02)), etc.
Options to customize, Steering dampers, Tires, Rims((Lightweight)), Exhaust systems, Powercommanders, Short Shifters, Carbon Fiber Bodywork. Give the depth of GT to TT2, and also provide visual customization, sponsor stickers, changing color,wheel color, etc.