Don't know about the specifics of your Katana or V&H, but if a manufacturer says that their slip-on does not require re-jetting on your bike, then you should be OK. MC's run lean (lowish fuel to air ratio) in order to pass smog. Almost any aftermarket exhaust is less restictive than stock so more air/fuel is run through the engine. Usually this means that more fuel needs to be run through the carbs to match up with more intake air. Re-jetting to larger jets increases the fuel to air ratio. If the slip-on is not significantly less restrictive, then no more fuel is needed. Check your pipe for residue color after the new pipe has been run some. If it's white/light grey (or if it the exhaust "pops" or backfires a lot), you're probably too lean and probably should re-jet. If it's dark grey, then OK. If really black/sooty, then too rich.
Last edited by RayO; 05-31-2002 at 01:10 PM.