just... There's another thread were we discussed this. Here's a post from it in regards to the APS car that did 307km/h... It ran 307km/h in early 2004. They had to fit 18's and a 3.23:1 diff ratio behind the T5 gearbox to achieve that speed. (The car also had better tyres and AP brakes). Probably the key point for anyone thinking that this type of speed would be a good idea is the below statement. This is from the driver of the car... Make sure you read the last two paragraphs. Speed is one thing, whether the chassis and aero can handle it is a whole other ball game. Power is the other big factor. For example, the Veyron only needs 270HP to reach 155MPH, which isn't much, however, it then needs another 730HP to do another 98MPH (253MPH). Then to take it one step further the Veyron SuperSport needs another 200HP to do another 5MPH (258MPH) and that's with a body and chassis designed for speed.