Some aftermarket fairings are really good, fit and finish.
Others, not so much.
I've seen alot of aftermarket fairings over the years, and from several manufacturers, and even though some brands are better than others, they are never perfect, it's always a bit of a gamble.
Also, oem/factory Gen2 Busa fairings aren't the best fitting things either, as even though they will bolt on correctly, the body lines don't always match as they should.
If you're picky, beware, you can spend a Fortune trying to get perfectly aligned fairings, but oem will Always be your best choice in that.
If you want something that looks good from 5' away, and small imperfections don't bother you, then most aftermarket fairing kits will do.
I am restoring an '03 Gsxr1k now, and it came with new in the box aftermarket fairings.
A matte/satin looking black, a nice finish all things considererd...with the exception of a White chip on the front fender.
Rather than mold these in black, they were molded in white, then painted black(to me that's a special kind of stupid), and they will do fine for what I need in the meantime, but that is an example of what to look out for when ordering aftermarket fairings, find a set that are molded in the main body color, so chips won't make it look bad.
I can see my nice new looking satin black Gsxr...dotted in white rock chips, lol,
I'm going to ask the guy powder coating my gas tank if he can powdercoat plastic(some can), so that is another option, depending on where you live and what services are locally available.