You should understand, 99S is a spin racket, not like conventional rackets with more and denser string patterns.
As such, tension on 99S needs to be higher.
Tension on racket's such as Dunlop300's and HeadYouMids can be as low as 40, and still play great.
Recommended tensions are a guideline for those of you who don't know what to string your racket's at.
Lots of Open level players use high 30's to low 40's their mid+ rackets.
I understand uber open pattern need to be strung tighter. I just disagree with your take on dropping tension vs increasing weight. You have your method. I have mine. And you don't need to instructor me in stringing basics LeeD. I understand strings and stringing. I tend to string about 3-4 of my own frames each month.
Even my 16x19 patterns are strung at higher tension. Low Tension doesn't work for me. I own Blade 98 frames (16x19), several Wilson Pro Opens (16x19) and I used poly/mult hybrids in these frames. I owned three Dunlop 300 and got rid of them for my Pro Opens thankfully four plus years ago. Dunlop - really unsure how or why they remain in business. Their tennis balls are horrible. The have very few frames that appeal to rec players. The 400 line was definitely a huge hole they seemed to fill nicely between the 300 and 500 line. But still, it's Dunlop. And Dunlop is a pretty lamp tennis company compared to the others IMO. A local dealer sells : Babolat, Wilson, Head, Volk, Prince, Yonex, Tecnifibre, Pacific, Solinco, and Asics. He dropped Dunlop - Why? Because they don't sell. Why? Because most of their frames stink. Why? Because Dunlop makes them and they really don't get it. See a pattern?
And by the way, there are lots of Open Level players stringing their 16x19 frames in the 50s. I add weight and it works from me. Dropping tension never worked for my game in a 16x19 Pattern, but adding weight certainly does.
My 342 gram Steam 99S frames work for me in both singles and doubles at 4.0 and I hope to finish my USTA season with a overall 0.75 winning percentage are higher.