The recipes are a bit off I think. It makes little sense to use the x1 and x2 recipes because only yellow belts have an increase in raw materials. Due to this, a express belt x1 versus x4 is the same iron difference as a yellow belt x1 versus x4. This also allows you to run underground express belts at only 15-20% of the cost it'd be to run normal express belts.

If you want to match the distance to cost ratio of normal belts you'll have to adjust the iron gear cost. So 40 iron gears for fast x2, 80 iron gears for fast x4, 80 iron gears/8 lubricant for express x2, and 160 iron gears/16 lubricant for express x4. This runs 520 iron for express x4 which is roughly the same as it'd cost to run normal express belts the same distance. Super expensive, but that's what the developers intended for top tier belts.

I've made this tweak for my game, here's the files: https://www.sendspace.com/file/mdo5xy

You raise a few very valid point. I'll start off with the cost balancing.

I wasn't really concerned with the material cost. But truthfully, the way Factorio has it setup for the vanilla underground belts is a bit odd already. To explain; for the vanilla belts you pay 5 belts and a few gears. but the actual reach from the underground to underground is 6. for the x2 the cost is 10 belts but the actual reach to line up with being 2 vanilla belts is 12, and the ratio goes from there. for the x4, its 20 belts, but the reach is actually 24. I figured in an engineering sense that the gears paid were just for the mechanism that starts the belt going underground and brings it back up again, the belts that go into the recipe being the distance decider.

even just ignoring the 'mechanical' thoughts listed above, the cost to distance ratio makes no sense in an of itself in vanilla and this is just made worse when offering x2/x4 of vanilla.

I'll will go over the recipe's and make it so that 2x/4x are x2/x4 the cost of the vanilla to balance it a bit more.

As for the research, two things there;
(1): this is my very first mod and I am just learning how to mod. I haven't yet figured out how to make it into a research.
(2): Making the x2 and x4 pipes or belts require additional research makes no sense to me. you already researched the underground belt technology, why would you need more research just to created extended versions? its the same design of how the belt goes underground and comes back up again, you are merely extending underground section.

I just edited my post, I uploaded my files if you want to take a look. I adjusted the iron gear and lubricant costs to match (roughly) what it takes to run normal belts the same distance. It's not perfect, but it's in the ballpark.

I agree the vanilla recipes are odd too, just trying to get the raw material cost in the realm of what the developers intended for these long of runs. Right now its far too cheap in my opinion.

I also agree with your logic of not needing research, I edited it out when I uploaded my custom files - then saw you already posted. ;)

P.S. Great mod, hope to see it updated when 0.15 hits.

only just now noticed the edit you did to the original post. I was actually already writing my response before you edited it.

I haven't looked at the download you offered, as I was in the process of tweaking my own files. 0.0.3 has the rebalanced cost to be 2x/4x of vanilla.

You bet I will update it to 0.15, I'm eagerly awaiting for 0.15 to hit. keeping my fingers crossed for the liquid train car and the pumps.

Dang your fast.

Great job, everything seems good now. Your new recipes are better than mine were, so no worries. ;)