My problem is that I've heard that they are all so inaccurate that if I buy a 70mph one it might go off the end of the scale. Equally I don't want to buy a 90mph one and only use two thirds of the scale.
To give some sort of clue, I have a well set up SR190 stage 5 tuned with an ancillotti silencer, 25mm phbl and varitronic ignition. After it's run in I'll be getting it set up properly on a dyno, so at a guess I'd say 14bhp which probably equates to 65mph ish from what other folk are saying about their top speeds.
Or I could just get a 120mph one and exaggerate to everyone I know

Recommendations from those with experience please.