business process mapping & M&A

Hi guys,

We are doing quite well when it comes to doing DD and closing deals.
Now: integration is a different ballgame where we have had various degrees of success.
I realized a few times that at the fundamental level it comes from a lack of prep work on the existing processes of the target co and an analysis of how they compare against ours. It creates frustations on both sides...

Have you guys seen any good resources to learn "best practices" on how to do such operational processes mapping/analyses?

Thanks