It doesnt work like that. The engine will still rev at the same RPM per MPH.
So a 130bhp car as standard that does 70mph @ 2,200rpm that has had a big turbo etc etc running 280bhp will still only do 70mph at 2,200rpm.
MPH vs Revs will only increase if you increase revs, so take the limiter off or up. Which on a diesel is pretty damn usless indeed. As By 5,100rpm (limiterish) you have very little power due to the way diesel and the engine works.
Indeed.
In terms of what a leon will do in 2nd it will achieve about 58 on the clock tho little point in going that far as the power dies rapidly after 4500 rpm any way unless you have a car which has a high map on it and they usually go all the way to 5200 rpm with little drop off in power.
Glynn