I have a 2003 predator 500 that I bought 3 years ago. It used to be very fast and I would always beat my friend's 400ex by a lot. About 6 months ago I put in a K&N air filter and rejetted it by dropping the clip on the needle jet one notch and putting in a 175 main jet. After I did this it was much fast, however, recently it has lost almost all of the top end power it used to have but still has the low end it had:dunno::dunno: (if you have ridden a predator you know they have a lot of top end and hardly any low end power). I always change the oil on time, and I just recently had the compression and valve clearance checked and they were both fine. Spark plug is also new. I haven't done anything to the carb since I rejeted it. The top speed has also decreased significantly, I clocked it at 80mph after the filter and now its top speed is only 63mph and getting beat by a 400 is not something I am going to get used to. Any thoughts would be greatly appreciated, the mechanic can't even tell me what is going on.