[GreenSquirrel]

There is some merit to this although it's effect on mileage has yet to be credibly tested but here it is; exhaust valves create backpressure at low RPM's (when the engine is cycling smaller volumes of exhaust per minute) but open to allow full use of the cavernous exhaust pipe, it allows the engine to get a small bump in hp lower in the rev range, my question is has anybody tried exhaust valves to nurse the engine during acceleration at lower speeds for the purposes of mileage/fuel-conservation? I intend to give this a go on my next vehicle but would like to know what others know/have experienced about this subject.