I'm talking about you driving it in 5th gear numpty, when you drove it you took it just past 6k in 5th. In any other gear it has to be taken to 6.5k without a doubt (and you did). It leans off after 6, thats why I got ya to let off.
172mph was worked out using the gear ratios etc.
7.2k on 215/40/17 would be 174mph providing it could pull to that rpm in 5th.