Have not tried going 100mph Gary, But I have been over 4000 rpm when I was passing on a 2 lane road. The tach redlines at 6000 so the block at 4000 @ 100mph must be software then? Original post wasn't clear. If it had been true then I would have probably been in trouble on that pass. I was actually very suprised when I punched the gas and it took off so quickly. Definately not a mouse of an engine