It is surprising that the Sportmasters are slower at 110+ mph than the std. Bravo lower at the same "X". From what I have learned in back to back comparisons, the Sportmaster lower unit is 1 to 1-1/2 mph slower than the IMCO unit at the same x dimension ( Two cat's and one "V" ). These comparisons were at 105 - 115 mph. Most opinions related to the speed difference were skeg length or thickness. I wonder if the water pick up design on the Sportmaster vs. the IMCO or the std. Bravo unit is causing a decrease. As there is a chance that the speed loss is related to this, maybe you can temporarily plug a few Sportmaster water pick-up slots for a test.
Could you have a temporary loss of HP that is effecting the test results?
If you need your 1/2" spacers back, I not using them... Remember, it's all about the hunt.