That site has excellent tuning advice.

Unless they are REALLY long, I'm 99% sure your arrows are too stiff (over-spined). You may be able to fix this by adding weight--heavier point, brass inserts, etc. Cutting them shorter will just make them stiffer. The weight you may have to add will probably be extreme--like another 100 grains or so.

My bet is, with 125 grain points, you'll need a 35/55 spine or something in that area.

Chad