I have the ARROW 71036CP - Full Race System in full Ti. I believe that you would be lucky to gain 3-4 RWHP with headers alone.
IMHO, $1800 will buy a Microtec ECU that will transform your bike, and deliver miles of smiles. Forget bolt on's, fix the throttle. No more high temps. You won't regret it. You will get your HP increase, with manners
Chris at X-Bikes is your man.