TSS has a EDMI in our 235 Pawnee for over a year and think it was a good investment, although, at times I wonder if it tells us more than we want to know. We had both CHT and EGT at higher limits on tows. EGT unexplainable after several inspections. Having cowling louvers installed to get the CHTs lower. The cooling monitor is most useful to avoid shock. Keep below 30deg change while reducing power. The power decrease to stay less than 30 keeps the Pawnee level after release, but as temps stabilize and power keeps coming back, you're soon doing 110mph and 1800rpm. Total tow time is about the same as with previous 2000rpm/100mph technique.