How do you get the bentley speed 8 car in gran turismo 4 past 300 mph?

i finally won the bentley, n ive heard about a bunch of different people getting it to like 335 mph. i have put on nitros and the stage 4 turbo kit and messed with the transmission a little. please help me out. thanks.|||it goes past 300 when the Vtech kicks in!!!!!|||Im not sure as I havent played it, but on previous gran tourismo games, after maxing out the car in upgrades, make sure you have it maxxed. Try messing with the gears again, if you put the gear ratios closer the car will shift sooner making you accelerate quicker ( if they are too close it just slows u down). If you make the gear ratios larger, you wont shift as often and you can reach a higher max speed, but will take a while to get there. Messing with the gears should work unless its some type of cheat or something that im unavvare of. They had one of those on the red suzuki racing car esquedo or something like that where it would do a wheeli and hit 200 some almost instantly. Hope that helps.