i beat this game a few weeks ago, and yes the final route is hell. like brandon, i recommend the angelus and i also recommend learning good nitrous conservation. don't use it too early in the races, and if you do, make sure to keep close to 1st place throughout the race. also, learn to block cars behind you better. not only does it help increase your nitrous, but you also gain a better lead by slowing them down.
good luck friend. it's one hell of a route.