when you are saying that :"it tracks to the left even with full right trim" do you actually mean that the plane tracks left with full right rudder deflection?? If this is the case something is wrong because the Prangster is good on rudder inputs. Do the following: install two spacers in the top left engine mounting hole between the engine mount and the black plastic "firewall" (viewed from behind the aircraft) to buid in some right thrust. However, i guess that the engine itself is probably installed on the engine mount without any right thrust, so either get a new engine mount and install the engine with some deflection to the right with regard to the engine/engine mount centreline or install the spacers as i mentioned. Also, bare in mind that this plane is a tail dragger but has NO tail wheel which could also cause it to steer left. The 40LA is a good match for this plane. There is a "3D" version with a different wing and larger control surfaces. If you decide to go for it sometime in the future, you could upsize in engine and install a 46LA, you do not really need more powerful engines. Check them out at www.jperkinsdistribution.co.uk SMC (Sussex-Model-Centre) stocks everything, they also have on offer now the OS 46LA for 52GBP