Greetings from finland.
I just read the topic. Best OM606 has over 3bar boost. Also you asked how to increase fuel flow from pump, What comes to stock pump its quite impossible, only way to increase fuel flow is replacing the elements and you need OM603 IP to OM606. Stock elements are 5.5mm on 603 and 6mm on 606 with 7mm elements you get almost 500hp.