Cingiale, are you sure your arrows are tuned for perfect flight? I would think that the 2018's with that much point weight would be a bit weak in spine. The reason I ask is that the soft plastic tubing will weaken the spine even more. Anything you add full length to the inside of the shaft, that adds weight, but has no spine of its own will weaken the dynamic spine of the shaft. The Ribteks heads are good and easy to sharpen, but weren't the best in the penetration tests I did. The 160 Grizzly or STOS did better.