I bought some older "Deore XT" compressionless derailleur housing from eBay a few years ago for a good price. I want to say it is 5.5mm thick whereas OEM Shimano housing is more like 4.5mm thickness. So it takes a different ferule. But I really like it because it is extra stiff and it seems to not degrade over time. Not sure if it would work for applications of newer brifters where the shift housing is routed all under the bars. I also am using Jagwire burnished stainless cables. I was told these shift much better and don't develop micro burrs like the some of todays Teflon coated inner wires can. So you don't have to change them annually if you don't want to.