POWERMAX8500 Data Reduction Ratio 5:1 DRR Guarantee

Hello All. We've a couple of PowerMAX Arrays. We were guaranteed(certificate issued) that we will get great DDR (Data Reduction Ratio). 5:1 DRR guarantee.
So indeed we are getting good DRR ratios and are very satisfied with them. Like PMAX8000 gives us 3.2:1 and Overall Efficiency=5.1:1.
PMAX2000 is giving 3.5:1 and Overall Efficiency=5.3:1.
PMAX2500 is giving huge DRR 8:1 currently. 
Now a new PMAX8500 is arriving soon and we have been guaranteed to get 5:1 DRR(guaranteed).
We know that at the time of commissioning DRR ratio is setup by EMC CE/PS(in bin file). And, ratio during the initial usage of the PMAX may vary, but the moment PMAX reaches 70% usage and above, then the real thing comes into play and it will make sure we get that Ratio(pre-defined in bin file at setup). So, the question is can we ask EMC to set it to some lower value at the time of initial setup. We don't want this high DRR ratio. And, if we do that, what are the 'pros and cons' of doing that. We don't want to loose any overall array wide performance or something unusual happening. At the same time we don't want this high DRR rate as well. And, 2ndly the install engineer can set it differently(if we ask) or he has to setup it like that during initial setup in DC. Please advise.  Thanks.