Hello, Jim. I had a 2002 Mean Streak 1500. The engine is just plain noisy. In my opinion 48K is too soon to dive into the engine if you have no other problems. It is true each lifter has a filter, but these usually only need replacing at engine rebuild time. You also have two air/oil separator screens that are inside the engine case right close to the crankcase vent tube at base of front cylinder. These are not serviceable except after engine is disassembled and crankcase is split. Another problem this engine has is that cam chains will eventually stretch out further than the spring-loaded adjusters can reach. Some people put extenders on. I just pulled off stock adjusters and added manual adjusters that I got from APE Race Parts. They are the same adjusters that are used on the old Kawasaki Concours. The manual ones leaked slightly where the stock ones did not. If you want to improve sound of engine I found that using Lucas Upper Cylinder Lube in gas tank worked wonders for high mileage bike. I sold mine at 62K miles and only problems it had were some pinging and some oil weeping around cam chain adjusters and cam plugs.
