well the thing about power are not so simple & changing racket are not significantly boost up power.
Ofcourse stiffer racket had higher max power ceiling but require more power before unlocking the potential. Many times club player going for demanding racket & burdening their games. Eventually when they try less demanding one they found out able to hit harder. Not sure if its your case or not as both OG99 & DZS are pretty demanding to.
So far i think ZF2 are the most hard hitter racket, being the stiffest & the head heaviest of all thus carry the highest potential of max power, but to unlock its potential the requirement are pretty high. Not to mention you had to hit with it repeatly for a whole match. The energy cost are high & will deplete you pretty fast.
Anyway which 99 & DZS you own? 3U or 4U? If its 4U, maybe you want to try 3U. It will hit harder if you able to handle the weight & swing as fast as when you use 4U coz it carry more weight. But again regardless, it wont double your power, just hit abit harder.