Fair enough
With that said, I think you can do better than K&N. At least for filter elements.
There's nothing too special about the plumbing. It's a tube going from filter to intake that holds the MAF.
The considerations I'd place on importance are:
- The box itself. Where it pulls air from, whether it be from outside air, or from the hot engine bay is going to make a difference.
- Whether or not you can use the maf turbulence screen
- Availability of parts
Figure out which airbox you want to use, determine what sort of dimensions you have to work with, then call around and see who makes a filter element that meets your criteria.
This is worth a read
https://nicoclub.com/archives/kn-vs-oem-filter.html