I'v been flying my US 40 with a K&B 65 Sportster. I'm wondering if I should switch it with a lighter 46 BB engine? The K&B gives loads of vertical, but do to the extra weight of the engine and 5oz of lead in the tail I think it is hurting my overall performance. It doesn't seem as nimble as my old GP Big Stick 40 that I had a .46 in. With the K&B I am still a bit nose heavy, so could that also be hurting my performance? Has anyone flown one with a larger engine vs. a smaller engine like a 46FX? Thanks for the input!