Knocked Hard (R117) car parts are one of the biggest expenses in this game. You should only be upgrading if you don't think the part will get you through the race.
Separately, there's a policy in place in this game for managers to use their real names (which I think is what Sonny Long (R136) is alluding to!) - better to change now if you can.
The forums and help pages are really great for newcomers. Take a read through and ask any questions you cannot find answers for.