VTA dump valves...fact or fable.
1. power gains...no, never, ever
2. smoother pick up between gear changes.....ever so slightly, nothing to shout about.
3. increased fuel consumption........not thtat i ever noticed running one for 3 years.my give you some pops and bangs through your exhaust
4. Fun/chav factor...scaring granny's at crossings..........YES.
5. reliabilty.......nothing serious happened to my scoob that wouldnt have happened anyway.
6. Piston or diaphram type....most will say piston type.
7. would i have another for my Hawkeye...not at the present...im skint...lol