I was lurking on the BNO Board yesterday and someone has used a rubber belt 13" by the width of the bus to create a vacuum to force more air into or out of the engine compartment. It was placed under and forward of the engine. Has anyone else tried this? If so what did you learn?I also would like to add louvers on my engine door so will monitor this thread.Hope I'm not hijacking this thread too much, sorry Tom C. Happy Trails,PaulDreamscape