I tend to agree, however the stock intake is restrictive...but so are some aftermarket "performance" AC's. I was dynotuning a new exhaust and the company had put a Performance Machine on the bike. It was producing 74 HP & 106 TQ, which is stock. Pulled the filter and immediately the output was where it should be for a stage 1..i.e. 81HP and 110 TQ. So performance wise, knock the plugs out of your stock slip-ons and spend a little coin on the AC and PV3 and you get a pretty good step up in performance for the price.Also on stock engines exhaust and intake do nothing to increase performance. As for the exhaust, the best power numbers come from the stock exhaust, no one beats it period. Lloyd Greer of Lloydz performance states this and dyno charts on Fuel Motto's website show the same thing. The air intake on the stock bikes is pretty optimized. You might see 2 to 4 HP on the top end at 5400 RPM, so if you drag race wide open it makes a difference.
As far as exhaust, the stock header with CAT is hard to beat. The Jackpot Header will match or slightly increase and greatly reduce the heat. One of the best exhaust I've found is the Rinehart Slimline Duals. It flows very well throughout the complete RPM range.