You can run B18A or B18B camshafts in our engines but they're a wee bit too long. Also, our engines have an exhaust cam-driven camshaft position sensor, while the B18A and B18B engines do not. If you wanted to use the exhaust cam out of one of these engines, you'd have to get a notch cut into the end of it so that it could drive the sensor. You ~can~ run the intake cam without any modifications, but be warned: it's too long, and the cam sprocket bolt will chew up the inside of your valve cover. Of course, this never happened to me! Well, okay. It did happen to me.
I just had a head worked on at a machine shop, and I brought a pair of B18B cams there to get a notch cut in and to make both cams shorter. I got all the stuff back, and now the cams are the right length, and the notch looks like Soichiro put it there himself with a big, sweaty machine.
Just as a side note, I think the B18B exhaust cam is a little bit hairier than the B21 exhaust cam. I haven't driven the car yet 'cause it's still in pieces, but the head is on, and I know I'm going to have one hell of a valve lash to do once I'm ready.
That is about all I can tell you about LS cams. Mine came out of a '96 RS, but it's all the same shit, different bucket. I can only think of how hairy my car would be with performance cams for an RS...
If you want some info about true performance cams for your A5, you're going to have to search 'cause I don't know anything about 'em. I know coltcams.com will grind your stock cams for you, but aside from that, I don't know shit from shovels.