My 17 BTX is stock everything. Purchased new last year and now has 1000 miles on it. I use Yamaha 0/40 oil, still has the stock plugs and battery, not sure about ecu flash and run regular pump gas. I have been having cold start issues since day one. -20c it a crap shoot if it will start and any lower than that I really start having my doubts it it will start. Yesterday it was -22c and I didn’t use a booster pack and it almost never went. I have been testing cold starts this winter with a booster pack. It was -33c this morning with an air intake temp and coolant temp of -33 and volts at 11.4. Hooked the booster pack up and it fire right up in about 5-10 seconds of cranking. This is the third time this winter I have tested this at -27c, -30c and -33c and it has started every time. I always keep holding the key on for a few seconds once it’s started just to make sure it stays going because the second try after it stalls always seems to be a much harder start. Not sure about others but with my sled it is clearly a voltage issue.