I wonder if sportmaster lower units steal speed when run less than 85 mph gps compared to a lower unit as XR. According to Merc Hi performance they only reccommend a sportmaster lower unit for outboards if running in excess of 85 mph. If not it steal speed. The main reason for sportmaster lowerunits is high x dimension (low water pickups) / eliminate blow out.

Any ideas?

Cheeeers, Toffen G