Hunting for idle is a classic symptom of lean condition. Not sure exactly how your bike is set up, but if it uses a closed loop system with an o2 sensor it's probably sensing that your exhaust is crazy lean and dumping lots of fuel (or at least as much as it can trim, usually 20%) into the bike which helps but doesn't help enough to read stoichiometric at the o2 sensor. I'm no efi wizard tho, more of a carburetor guy.
Problem is, a guy with more engineering degrees on his wall than you designed the exhaust for that bike, but you decided you knew better than him.
Put a good stock exhaust on it and all will be right, or spend a few grand on a full system and a fuel controller and a day of dyno tuning and enjoy the gains.