One of our members has the same OS 50SX installed inverted in his U-Can-Do 3D .46, and the engine runs great without onboard glow driver. If you take the time to tune the engine right, especially the low end, then you won't need onboard glow driver. To me, onboard glow driver just adds extra weight. It's also one more thing to worry about. It's OK to use onboard glow when the engine is still breaking in. When the engine is fully broken in, it should run fine inverted without extra help.