I'm fooling with a Magnum Pro 40 with a modified RJL head. I doesn't have a lot of time on it yet. It is turning around 8,800-8,900. I'm running it with a control line venturi and spraybar. It flip starts readily at the running settings, and takes maybe 20 seconds to smooth out completely from cold. Havn't tried the muffler yet, but should make no difference. I've been running it on Davis 1/2A fuel which is what I have at the moment.

Jim