This is a 2014 MAJOR UPDATE version of the Ultra FPS & ROF series book. With feedback from customers and reviewers we further develop the original mechbox guide to additionally cover manufacturer specific tech info for airsoft FPS/ROF optimization. The primary goal of this guide is to help you improve your electric airsoft AEG's FPS and ROF in cost effective ways. Different mechbox modification techniques are covered. Additionally, we address the issues of air tightness and battery configuration which are outside of the mechbox but are still highly relevant to the overall airsoft AEG performance.