I got my 97 Bandit with an aftermarket Vance and Hines Exhaust. I am sure it was not rejetted at all for this. I noticed that it does surge a little and idle a bit rough when cold. I also used compressed air to clean out the stock air filter a bit.
I am thinking this combined with the exhaust is making it run a bit lean. On the stock 97 1200 settup, can you adjust enough the idle mixture to relieve this, or is a rejetting of all carbs in order?