exhaust / dyno question

[darrsi]

I've had my bike on the Dyno 3 or 4 times over the years when having the carbs properly cleaned out and the fella who does it is more like a bike surgeon than a mechanic.
I tried having it re-jetted once but that never really worked out and i had it changed back to standard jets and it then ran fine again.
Another thing he always said was that for best performance you wouldn't get much better than the stock exhaust, but i just can't stand how quiet it is, plus it's not exactly easy on the eye either.