For my 34" Tele bass I recently built, I used a two way hotrod I made myself plus 2 13x3mm steel stiffening rods epoxied in to prevent rattles, one either side of the truss rod as Warmoth does. The string tension is very high on basses and even with the stiffeners it pulled the neck into a curve but the truss rod counteracted this no problem. I wouldnt go back to using a standard single acting rod after using double acting hotrods. When you fret a neck it often backbows and it is easy to adjust it straight before fret levelling. They also make routing a channel so easy. They rule!