NONE,,,,Had the stage 1 installed by the dealer....later sold bike to my son, he rides it regularly and it is without any problems...so far.....why do you ask this question.....In 30 plus years of riding Harleys...the only problems I have had is when I did something wrong.....it is called....customer abuse.....
Inner primary bearing at around 37,000 miles. Compensator at around 42,000 mi. No engine problems except for the time I filled up with 4 gallons and 2 of them were water. It wouldn't run til I pulled the tank, drained it, cleaned it and replaced the fuel filter.