Ok, rough guesses put him at about:
3500rpm @ 180kph (19.44rpm/kph)
4000rpm @ 210kph (19.05rpm/kph)
Let's split the difference... which gives us around 19.25rpm/kph. He tops out at around 4850rpm, which puts him at 252kph. In American terms, that's about 157mph. Of course, this assumes that all his instrumentation is accurate at all engine and vehicle speeds. I've run a Lightning up to 140mph, so I know they can go at least that fast.