I tweaked the recipes so each tier can be upgraded to the next. I also balanced the raw material cost to be (roughly) the same as if you ran above ground pipes/belts the same distance. As a result, some recipes are cheaper and others are more expensive. I also added some higher resolution research icons.
Neomore, feel free to use any of this in your next version. I tweaked it for my personal taste and thought i'd just share.
https://www.sendspace.com/file/oxptv9
