No noises what so ever. I made a few additional brackets for it so it doesn't move what so ever. One of the guys here in Townsville got one a few months back for his GTR. He mounted it dodgy as hell (he's pretty dodgy with anything to do with cars though), the whole thing moved side to side and when I saw it for the first time with some mates I said "that thing is going to fly off". Sure enough a few weeks later, it did hahahaha.
But yeah it's fine. Doesn't move what so ever it's on there that tight. Been at plenty of high speeds with it aswell and no problems there. My car is pretty low and it doesn't hit anything at all. I've order the additional carbon vortex generators for the side of it aswell so will install them and post some pics up soon.
If you buy one from PSI Parts, hit them up for the DIY install I wrote up for them. Plenty of photos of everything I did.