I was E-mailed this message from Mike at Big Gun yesterday evening:

"Dear Sir,
Thanks for the email to Big Gun. As for your question about the Raptor. Let me answer them for you! we have been very overwhelmed with email regarding our new Yamaha Raptor exhaust. This exhaust is the same exhaust system that is currently being used on all the Yamaha Factory Raptor atv's nationwide. This new system has proved its merits by leading the competition at the Baja 2000 only to suffer a broken steering arm 5 miles from the finish with a 45 minute lead over
second place. The team started with the same exhaust they finished with! This exhaust system was designed to give better power throughout the entire power range. The power will be very noticable from top to bottom with our increase on a 49 state model from 10-11hp overall with our complete system and, 6-8 with our silencer alone. Also the complete system takes off up to 6-7lbs of weight. The system utilizes mild steel contruction on the exhaust system and our new internal and external aerospace ceramic coating that lowers the exhaust temperature by 300-400 degrees and creates 2% more hp also this coating won't flake peel or dis-color. You will also need to re-jet the carb quite a bit from stock. This is mandatory with any Big Gun Exhaust.
The jetting recommendations are:

27.5 pilot jets on both carbs
150 main jet on left carb
155 main jet on right carb

For more info contact us at (909)948-7029
Thanks,
Mike"

One thing that jumps out to me is the jetting changes. Do other exhaust manufacturers recommend this much change with their exhaust? Later.