level 1 is stock, level 6 is 100 horse, speed loader is 126 horse, 2 is 20% added power, 3 is 40% added power, basicaly every level (2-6) is 20 extra horse. I have the six gun with pda on my truck and I love it, levels 2 and 3 added about 3 mpg, level four it starts dropping but 4-sl is adding fuel and timing, level 2 and 3 is just timing.