Step testing is process used in EFI tuning. You use the dyno to load the engine. You work you way through the KPA and RPM grid and go through your Auto Tune. You can a mess with different AFRs and Timing. For something like the Sniper. Probably set your timing and AFR. Then just Dyno through the Auto Tune. Will use 3500 RPM as a Example. Bring the engine up to 3500 put some load on the engine hold it say 3-4 sec 30 KPA@ 3500 RPM. Then back it back down each time then roll up to the next KPA@ 3500. Say it's 35 KPA@ 3500 RPM then 40@ 3500 45 50 55 60 KPA@ 3500 so on. Of course the dyno Op will have to keep applying load to reach the upper KPAs. Thats whats nice with a dyno and a Auto Tune feature or what ever Holley calls thiers. You can go through the Auto Tune in a few hours. Where it would take days or weeks for the engine to see all areas of the map. Way Safer too. I probably didn't explain as well as someone else could. but that's ballpark explanation. Anyone wanting to read some good stuff on EFI. Highly recommend the EFI books by Greg Banish. Helped me alot with doing EFI on Harleys.