How high tension can a Cab 7 Long take, before it will warp? The model I have is a 2U, and Yonex has rated it up to 20 lbs. But many ppl string over the recommended tension anyway (like at 24lbs+) on rackets that are only rated for 22lbs without problem. It is a carbon graphite racket with an oval head, if that has any influence over the tension that it can take. Also, this racket is in excellent condition; it's hardly been used. When I went to get it restrung, the stringer insisted that at any tension higher than 20, it will warp. And I wanted to string at 22 or 21. Anyway..the 20 is at least much better than what I had before...which was just factory strings.