If you have a 1986 GSXR 750, it may add horsepower. The only test I ever saw was for a late-model CBR 600. The K&N lost several HP, but if you don't go over 10K RPM, you may not notice. The best thing about the K&N is it lasts forever, after washing and oiling. If you're like me and squeeze every last drop out of a bike (my three bikes average over 23 years old) get the K&N. Otherwise get the stock filter.