The Jagwire Pro Road brake cables have a short section of smaller diameter silver housing at the end of the colored housing that is intended to reduce bulk under the bar tape. Since you want that feature for both levers, it one lever to the first cable stop and trim the housing, then use the other for the other brake lever. Gearshift housing should be the same diameter and color for the full length of the housing. The other important tip is to use good quality cable cutter and don't try to fake it with tin snips wire cutters or cheapo cutters because it will cause you grief. Also be careful sizing the last piece of housing to the rear derailleur.