Until last week I was running nothing but the CaTCHER, about 4k miles. Before the CaTCHER I was running a comp box with the wire tapped. I only ran the box on 2x5. Never felt brave enough to play hard with it on 5x5. Any way, I noticed a huge difference in everything about the truck with just the CaTCHER. Power comes in a lot lower in the RPMs, pulls loads a lot better and EGTs are lower than with the Comp box. I have 4. 10s and my MPG went from 17s to 18s, actually had a tank that was 19. 6 had calculated with stock tires. The best thing about the CaTCHER is that the timing isn't too aggressive. I love mine and would be in severe depression if I had to give it up. The stock clutch will work fine with the catcher also. I've since added Mach 1. 5s and now the clutch is hating life. I would say the CaTCHER is the best single upgrade that you can make. Lots of usable power, in my opinion the comp box didn't make much difference until the RPMs were higher. GO WITH THE CaTCHER, YOU/HE WON'T BE SORRY.