I always have to chuckle when I read these decat/exhaust threads. Be honest, the main reason folks modify the exhaust on a 130+ hp bike that they will be riding on public roads, is for the sound. They want the image, just like the harley guys who bolt on the obnoxiously loud pipes. 90% of us old(er) farts who ride multis won't derive any real life benefit from losing the weight of the cat, or from whatever power gains they may get.
I have been fortunate in that my multis have run well with the stock exhausts. Fat ducs smoothed out the fueling. All of the mods I've done to my bikes have been for safety, or comfort. The bike is plenty fast enough for any public road, and I prefer to ride swift and silent.
my 0.02. YMMV
'12 Multi Touring these days
Yes, I do miss my air cooled multi...
Brand spanking new Thruxton R