I have seen no evidence that 2 steps hurt engines although I agree it sounds like it should...The functional difference between the 2 step and pneumatic limiters is mostly carb tuning. With the two step the carb is wide open so there are not any accl. pump concerns (ramp, size squitter vol. ). With pneumatic those are a concern. With a 2 step (or similar) I think you can mitigate your potential damage generation by how you use in I see quite often racers go in and get on the 2 step , some time even before the opponent has staged In my earlier days of racing and racing on a Full tree I preferred to Top bulb leave so I would release the TB on the top Bulb and and floor it on the second bulb. For those of you not using Delay boxes it becomes little tougher but manageable, Most recently I have tried and like leaving off the converter, no two step involved. better reaction time and very consistent.