Compression...

Moper's right on the money. One thing that hasn't been mentioned yet was the effect of altitude on compression. Here in Denver, you can get away with an additional point of compression (10.5:1) due to the lack of oxygen, keeping in mind the variables that moper has previously mentioned. The problem is, if I plan to run my vehicles @ less than 4,000, I need to back off the timing, hence the MSD in-cab timing control, which also gives me the ability to bump up the timing when mountain cruising (6,000 to 10,000+ ft.).

Oh yeah, those pump gas guys in Engine Masters are running "Rocket" brand fuel, far better stuff than the swill we get at the corner pump.