If there were more widely available factory resources, I would probably go with them.

I have a Nissan, and if factory-installed Nismo parts were available I'd jump on that, because if a company has a tuning division, then they already know the vehicle well, and their parts and quality would reflect that.

Plus, a warranty is always nice.

Even though there's a lot to be said for the sense of satisfaction for a D.I.Y. job, I wouldn't mind sacrificing some of that for reliability.

Besides, there's still plenty you can do on your own, you'd just have a better base to work from.