I guess it's no different than anything else, but it's a shame "car culture" insists on being so clique -ey.
I can't play the piano, so is it "cheating" for me to buy an album where someone else plays the piano?
I'm a marginal cook. Am I a poseur because I occasionally opt to go to a nice restaurant?
As long as I don't buy the album and tell people I recorded it. Or go to the steak house and claim to be the chef, it's reasonable. The same should be true for us. Many out there appreciate a good car with specific mods but don't have the time or ability to build it ourselves.
So, if the mods are done well, you can trust the builder, and they match what you were wanting - why not? If someone is going to be a douche canoe and sincerely hassle you because you didn't bust your own knuckles, then they've indicated their opinion isn't useful.
I don't know why we can't all support each other.
...except for coal-rolling, bro-dozer drivers. Eff those guys.