When setting up the bikes computer to operate at best efficiency, power, starting and operating temperature one needs to do this on a dynamometer. The dynamometer is a closed loop testing system with a brake assembly on the rear rollers. You are able to create actual operating values and record the engine performance. You can do the same thing with a fuel pack in fact many operate better if adjusted to the run conditions on a dynamometer. I used the Master Tuner to access the bikes computer then it is removed and stored until or if you should need to retune. The fuel pack stays on the bike and sends a signal to the computer to make it operate to the required values. The Thunder Max tuner replaces your onboard computer and after initial set up begins to change operating values based on conditions. Although I had one on a bike and I still had to have timing altered for best operations. The tuners like I used and the Harley Super Tuner or Race Tuner can give the operator of the dynamometer better access to different parameters. Such as the Master Tuner will allow you to alternate cylinders in an over-heat mode. The fuel packs are limited to what can be changed to the output of the computer by altering the input. They don’t actually reprogram the computer. Remove them and they go back to stock outputs.
Anyway in a nutshell either item can produce a good performing engine if set up correctly.

 

My 09 CVO Fat Bob with Rush 2" slip-ons and PCIII made 92 HP and 119TQ.
Gary