Could you please make it that when the ''Pipes and belts changes'' option is unchecked, the modded underground belts and pipes change their values to be in line with their vanilla counterparts? I'm referring to the advance and superior underground belts and the steel underground pipe
so their length would be closer to 5, 7, 9, 11, 13 not 5, 7, 9, 30, 40 and the steel pipes would have a length of 15 or 20

Also if there could be an option to keep the stack sizes unchanged from vanilla's

The stack size are already under an option. Anyway no, we don't agree with the ur belt option, but can easly make a plugin mod of it.

''The stack size are already under an option'' Is not though, that option makes even stacks that are not the same size in vanilla, like iron ore and iron plates and gears

Oh gosh.... ok ok... should be one line of code, so I will try to add this for the next update

Done