Stainless line are great. It may be a good idea to leave the top line to the master stock. This gives you some brake feel until you become acustomed to how much brake your gettin'. I'm new to this forum but I started riding on a 1981 CB900f. I just purchased my '04 919 (green) and love it. I build hot rods and restore cars so the bike will get painted. I already gutted the stock mufflers and installed a power commander (power commander is fantastic).
I removed the stock mufflers took off the heat shields. I then cut the exhust outlet off at the seem for the factory weld. Removed the insert and welded the outlet back on. It sounded OK but the cans picked up a resonance at 5000rpm that was way bad. I cut them open again an put the inserts back after cutting all the insides out (2 metal plates and the tubes). It sounds great now with no problems. My PCIII/USB fixed the fuel problems the bike was super rich even after exhaust.