In addition to the above, I'll add the intangible of having confidence that your bike is mechanically sound to handle those speeds. The best thing I ever did was learn how to wrench my bike and do my own maintenance. 40+ mph is no time to have your limit screws set incorrectly and throw your chain e.g., or have something loose because you don't have a routine of checking your own rig.

Either yourself, or get a good mechanic that you trust and keep your bike on a regular maintenance schedule with him. 40+ mph is not like riding the MUP to the store.