Here is some links I came across while I was trying to understand more about how cost index affects aircraft performance. These are articles from Boeing's AERO Magazine. I understand we fly simulators, but, flying simulators unrealistically is just gaming. :) Hope you find this useful.
http://www.boeing.com/commercial/aer...icle_05_3.html
http://www.boeing.com/commercial/aer...icle_05_1.html