saved me a alot when I was racing my cars. add bouncing around in the truck, hammering through a trail, get a little air born, watch how quick it will go to 8,000 RPM!! I have an MSD 6al with a 5200 pill in it.
My buddy had a tell tale pro comp tach in his race car, 9,200 with his 488 BBC! well built, it lived! but limiter went on after that!!