to make sure you guys are not getting wheel spin on the dyno ask the operater to measure engine rpm at the engine not calculated from roller speed and then after a run get them to plot engine speed against road speed,
the line should be straight if theres no wheel spin,ill get a printout if i think of it and show you

beware though if they do measure engine rpm from rollers line will also be straight so insist they use a engine rpm pick up