I would say yes. I have not run the 55AX, but I have run both the 95AX and 120 AX with mufflers and pipes and they both benefitted from having a pipe. I will add that I also found that running them with a pipe was helped with the addition of a Perry (or similar) pump. If you don't fly a lot of vertical maneuvers, then the pump may not be necessary. I was experimenting with the AX engines in practice planes flying Masters and FAI schedules.
Good Luck! The Calypso is a very nice flying airplane.