If you spray the de-carb through the intakes on a DFI it can run away on you and the mtr will shut off. Then you'll get a code 57 where it takes a lap top to clear the code so it will start again. Tilt it up with the plugs out and put the de-carb in the cyls and let it soak.
Try to add some Carbon Guard to the fuel. Give it a good run and re-test. If the lower readings was on the port side, almost normal. If on stb, a bit more to be worried about.
Are the low compression cylinders the two bottom cyls? Starting around 1994, OMC designed some of their V6 engines to have lower compression in the bottom two cyls. I know the 60 degree Intruder-type engines ran lower compression in their two lower cyls. Was a long-term reliability thing. You may want to call Bombardier customer service and ask someone about your engine: 1-847-689-7090
#57 is a code typical when people run on muffs and rev the engine in gear!!
It may even indicate a fuel leak into crank case from a broken lift pump membrane as well.
yes, i have the cable. we were able to clear the code. anyway when he sprayed that stuff in boy did it smoke, alot of carbin washed away with the water. hope this helps.. hey boobie let me pick your brain, no wake zone the motor runs rough as if its running on 5cylinders and not 6.. if i give it a quick shot of gas then back off sometimes this helps. i did change plugs.