I got to about 8000 rpms in 6th gear in my old rsx (16psi) before shutting down due to feeling of instability. This was on i-16 about 5 years ago now.

I'm not sure of the exact speed since i was past the 160mark on my speedo. But if I use my 8k rpms estimate, and a calculator, it comes out to about 180 with the wheels I had then. I voted lower however since I'm not positive and my memory could be off.