my buddy just bought a 660 grizzley and i talked him into getting a kit from highlifter which consisted of a tuned pipe, jets, spark plug,and k&n airfilter ok the problem is it didn't really gain any horsepower and well we had to rejet it because of the tuned pipe and with the sea level here we had to take out the jet and well it was like a 150 and we had to put in a 145 do you think this restriction of fuel cancels out the power gain he should receive and would it be alright if i put like a 155 jet in to let in more fuel any info would be greatly appreciated anything about gaining horsepower with his grizz

 

i got that same kit and mine got a shiz load of more power. i can ride wheelies like its a racing four hweeler now. I dont know how his didnt work.

 

jet up, and make sure you have the right spark plug gap.