Yeah, What Flash said. It's all about the tramp. I've seen worse than 6" for sure. Get your tramp back and crank down on it, should make it way better. Use a good quality low stretch line. If saving every ounce is not that important, just use a 1/4" pre-stretched Dacron, it works fine and is easier on the hands while stringing up the tramp. If it's still bad, I've seen people shim the x-bars using various methods. BTW the bow spreader is for the 'turbo'. By adding the jib, the forces want to pinch in the bows.

Hope that helps!