DB resource utilization

Hello,
Our application setting established 1000 dedicated DB connections to database, though only 10% of them are ever used. I am planning to change the setting and bring down the connections to 100. Before that, I would like to capture the current resource utilization so that I can compare the same after the change.
What are the parameters that will be impacted with this change (Memory etc.). How can I best benchmark the change?

Thanks

anyone home??
I would like to know how to benchmark the reduction in number of dedicated sessions (tangible results).

Thanks again

Statspack?