fontyyy wrote:Make up your mind, is it a complete waste of time or does it make a little difference to the power output?

There are no big gains anywhere, ever. You get a bhp or 2 here, another one there, another 1 or 2 somewhere else and suddenly instead of 62bhp you have 67.

I'll agree with Jan Thiel's assesment that this type of thing makes little difference, the spoiler is the spinning crank and rod, that creates much more turbulence. A very clever South African ex GP enginner told a his friend that spending 20 hours on F1 boat cases that it was a WOFTAM, left the cases stock(except for removing a few casting dags) the dyno nor a world class driver could pick the difference.I my local dyno can't pick the differnce between cases with and without this mod.
Big gains come from the ignition, pipe and specific time areas.