The acceleration runs, as usual, are the most revealing. Some of the runs had two people aboard, and some were just me so the acceleration times vary. However, in the quarter mile its the trap speed that tells how much power you're putting down: you can clearly see the trap speed go up from just under 99mph to over 100mph. This is certainly about right for a modification which is supposed to increase peak power by 8-10bhp.
Problems? Well, as usual actually getting horsepower numbers that you can relate to net/crank horsepower is tough with this style of instrument. That, plus the fact that I forgot my own 2000-2200rpm launch rule which added a tenth or two to my 0-60mph time. But that's what this whole idea is for... seeing what your car can do, and how best you drive it!