with 647hp, it should be enough to do atleast 205mph. If it can only do 180 with 647hp, then something is wrong with the tuning. The Nissan GTR with 480hp can do 190mph. If you want to get up to 230mph, you will need to get the power close to 900hp. But you will need to do alot more than just boost engine power, you need suspension upgrades, transmission upgrades and make sure you have wheels and especially tires that can handle that kind of speed. A set of Kumho Y rated tires should do the job.