talking about using the original drop bar calipers on touring bars. Drop bar levers are curved so when putting them on straight bars there leaves very little range of motion to engage the brakes. The mod is the slightly heat the levers and "uncurve" them some so as to allow enough lever travel to engage the brakes. Advantage can keep original vintage style levers, and hoods, no need to spend $$ on levers that wont match style anyway, guaranteed compatible with existing stock calipers. Cons, in theory could weaken levers and cause sudden catastrophic snapping of levers while braking although in actuality there is no reports of this happening after doing the mod. However dead men tell no tales. So theres that.