I put one on my 750F back around 1980 or 81. I bought it from Honda of Anchorage and they were asking the same price for the OEM and the K&N. The K&N was reusable, the stock filter was not, so it was an economic choice for me. I can't say I noticed a big performance increase, except my gas mileage didn't start dropping around 4000 miles like it did with the stock filter. I didn't change the jetting, didn't have to. I clean it about every 10,000 miles instead of whatever K&N advertises these days, but I have a habit of living at the end of long gravel roads. The filter has over 90,000 miles on it now, so it has paid for itself a few times.
A K&N thread always brings out the K&N naysayers. K&N filters are controversial because a lot of people say they pass harmful particles. People say they find dirt in the intake passages downstream from the filter. I never have. I believe that if people have that problem, they are not installing it correctly. You have to use the sealing grease. My bike is just shy of the 110,000 mile mark and still uses less than a pint of oil in 3000 miles. I think if the K&N filter wasn't doing its job it would have shown up in top end wear.
