ST 2000, 2500 & 3000
The 3000 (1.8 cu. in.) and newer 3250 (2 cu. in.) had a slightly taller, but identical looking, case, somewhere around a quarter inch.
The smaller 1.2 cu. in. 2000 came out first, followed by the 1.5 cu. in. 2500. These engines got their max hp at 13,000 and 10,000 respectively, according to Super Tigre. 16 inch props were normally used on the engines.
When the 3000 came out, many people tried to prop them with the same 16-8 or 16-10 prop and found the 3000 didn't turn any better than the 2500. The Super Tigre literature indicated max hp for the 3000 to be at 7900 rpm. An 18-10 prop works nicely. It took several years for the scale guys in my club to warn up to the 3000 and use a large prop. The engine is a lugger. the 2500 and 2000 turned up a lot more. Finally guys started prtting 18-6 and 18-8 on the 2500 and were pleasantly surprised.
The carbs are a diferent story.
On another engine, but in the same area, I do not own an MDS, but I wonder if many people with the MDS 1.48 are under propping it before it is broken in. Running a couple of tanks through it with a 16 inch prop, then leaning it out to the max on 15% fuel appears risky in my opinion. Seems to me that an engine of that size should be using a 17 or 18 inch prop. All my big Tigres have needed a lot of rich running and 2 or 3 gallons before I would say they were really broken in. I would expect the same for the MDS, but them I have never owned one.