On My KLX I removed the whole air box, filter, carb assembly and replaced it with a keihin FCR41.
Anyway I researced ram pipes and decided I could make a better one.
I did this and fitted it with a pod type filter (flat end with a hole in , no rubber molding).
First test ride and the thing would only do 75mph, came home, took the filter off and went out again, 90mph in the same place, the carb had been sucking the filter in.
I made an aluminium thing to go in the filter and poke through the end and fixed it to the frame with a cable tie, no more filter sucking and I'm a happy chap.
Top speed is limited to about 95 by stability problems but man it gets there fast.
Clive W