Tony´s
Increasing the downthrust is something I have seen a lot with models that are designed for both glow and electric. If you think about it, a glow model has a lot of weight very low in the model. The engine cyclinder and the exhaust system. When I first starting flying my Partner back in 2004 it also pulled to the canopy slightly. But the way the Partner was done I could lower the motor batteries in the fuselage a lot, moving the vertical CG down and that solved the pull. With the Onas it needed just a bit more downthrust.

Chip
Just to add a little to Tony´s post about the vetical CG and pulling to the canopy. I have flown with Tony now quite a bit over the past year and have gained the utmost respect for his knowledge when it comes to knowing how to make a plane fly. This subject is where our opinouns differ just slightly and I am not saying either of us is wrong in anyway as everyone knows theres several ways to skin a cat.

Tony likes to fly with quite a bit more down elevator when inverted then I do which requires a more forward CG (Down thrust required to not pull to the canopy). I still like to push when inverted just not as much and when the model is set up that way the tendancy to go to the canopy goes away on its own. Again its just another way to do things. It will come down to personal preference in this area but either way will work just fine. Just my 2 cents worth.

Chip