Hi all, I've recently purchase a brand new Yonex ZF2. I've been wanting to tried it out for ages but can't find it previously around my area until recently. My main racket is 1 gen 4U 88D which I love it alot as it do packed a punch and navigate quite fast. My usual string is 66 ultimax with 27lbs for my 88D. I use the same setup of ZF2 but I find it hard to generate much power from most of my hits as the smashes seems to quite weak & I need to put extra effort to get the shuttle to baseline. Should I reduce the tension or try different type of string?