~3k for 80mph on a 5speed Turbo.
still, at 3k(
80mph ), my motor sounds are more pronounced than at 2500 rpm. "kinda" hums harder.
Also many cars I've driven change tone at 3k. not just the supra. (rx7, 300zx, etc)
Still, I like the sound of my modified 7mgte, Vband t4, & 3" exh pipes prolonged at 5k in 5th GEAR