I've heard positive things about tractor and implement paint, particularly a color called Blitz Black by John Deere. Unfortunately I think they fade more readily that rustoleum but I'm not sure.

I recently bought an HVLP gun for my compressor and played around with it the last couple of days, painting a muffler(don't ask why, it's just what scrap I had laying around).
Primer thinned 10% with mineral spirits went on like a dream, perfect uniform coat. I had one run because I didn't know what I was doing and held the gun too close. Full coverage in one coat with no thin spots. I didn't even prep this thing, I just washed it and scrubbed it with a soap pad thing.

Then I thought I'd throw gloss black on it. I had an interesting result. Orange peel was pretty bad but I got complete coverage in one coat, as opposed to the 6 it took me on my car. I may sand and buff just to get an idea of how it looks. I can say however that spraying, even with my cheap HF gun, was about 10x easier than rolling, particularly with the gloss coat.

Check it out:

(Note, the uneven areas are rust. I didn't sand this at all or prep it like I should have, I just wanted to get a hang of my gun.)