I'm no expert, but 4 degrees is really nothing. I was readinf the plans for the Sig kadet Senior....which is another trainer, and it had 8 degrees downthrust....plus I for get what the right thrust was...but it was a bunch. The reason I know it flies funny is I recently blost my muffler end in flight so I had to replace it. Wound up getting the whole muffler assembly for 10 bucks.....the Tower Hobbies brand. It fis the engine fine, but the canister is just a bit closer to the motor so it was coausing the ISO-Smooth mount to flex and push the motor just a bit straighter. I thought I had some major issues the way it was flying today......and then I started thinking (oh, oh !!! ) So I took my exacto knife and made a releif in the side of the fuse where the muffler was pressing so it would'nt be pushing sideways on the motor. Well problem solved.....flew good as new. So the engineered right thrust that is built into the plane.....or any plane is important. Leave it be and it should be fine


Adam