You install an after market air cleaner or velocity stack and want to get rid of the ugly stock engine breather crossover tubes. What do you use to make your engine breathe correctly without having engine oil mist ending up on your exhaust or on your right leg or, most of the time, both? It’s the question I get all the time. After testing many systems, I found out that the Doherty Vent Kit is probably the most efficient system to reduce the blowly oil mist. In addition, the Doherty Power Vent reduces crankcase pressure and prevents gasket leaks. Another reason you see it on most of my customs is that it is small and quite good looking, which is, as you can imagine, very important to me. Available for head or crankcase breathing engines, with kits for both Evo & Twin Cam engines. Doherty Machine.