You can check out various dynos on a link I posted on page 2. my 99 summit x 670 which is ho is 126.8 hp. You will also find the same motor in different models have different hp. The machs dyno tested much higher horse than the same motor in summits the 01 summit 800 is only 133, only 6 higher than my 670ho. The stock 670 has more than 90 hp, the old formula 500 has 90hp.The 05 renegade 800ho tested at only 131.04 rev summit 800 is 141.8.Thats 10 more horse, a year older and not the ho, but different model.