Need help explaining Data Domain's effect on SLA's

Ok, so I need some help. We currently have a DD2500 that is at 93% usage and we are in the middle of a data center consolidation. Because of this I need more capacity, which equals cost. Our IT Steering committee (mostly non-IT execs) are asking me to explain why lowering our SLA's (RPO and RTO) would not reduce the need for capacity. They think "if we change our SLA's for these systems from 12 hour RPO to 1 day, we won't need more resources." But it doesn't work that way since its the sheer amount of unique data driving the need, not how often we backup. And now my boss wants a PowerPoint slide explaining this all with pictures.

Any help is appreciated.