I've used OEM, Maier, and Full Bore. The full bore stuff looks the best, but I have beat the $hit out of the Maier stuff and it still looks good. My only complaint is that every damn type of plastic other than OEM will eventually melt around the exhaust coupler.
Fullbore's definitely aren't painted...is it true that Fullbores are painted? that's what a local shop told me.