One has to understand that there are a lot of factors involved. I do not know what the compression of the Quadra/US engines are, but it might be low. Too low of a compression ratio would cause problems keeping the glow plug lit without glow power. In that case, more methanol and/or nitro would be indicated to help keep the glow plug lit.

Generally if an engine operating on glow quits, (assuming the glow plug is good), or loses rpms when the glow power is removed, it needs either:

A. More compression
B. More nitro
C. A hotter glow plug (We are already running a hot, four stroke plug.)

Ours is a special case with the gasoline mix. Hence my remark about perhaps more methanol helping in your case; to keep the catalytic reaction going with the lower combustion heat involved due to lower compression. (Assuming that is the problem!)

Once again, another option would be to run full time glow power with a 3000 mah or larger onboard battery in those cases that have problems running without glow heat. It's still cheaper, lighter, simpler, and more powerful than spark ignition, and has no interference issues.

AV8TOR