As noted, more noise and more open (like drag) pipes means less back pressure (but higher RPM on the top end). However, without replacement of the air cleaner, you do not increase "flow" through the engine, hence no performance increase.
Performance (meaning HP, torque) are affected by your exhaust in several regards. The reason behind tuned header pipes is that the lengths and diameter are calculated to your engine needs, and believe it or not, the audio noise created from the engine is actually utlized to create a sound wave that helps prevent raw fuel from exiting the chamber. More fuel in combustion chamber equals more power!
The length of the total exhaust system will affect torque and top end RPM. There are math formulas that help determine all these factors, as both length and diameter are involved as well.
I have the SE II tips on my bike, with an SE air cleaner and the carb re-jetted to ensure I am not running lean. Lean means holes in pistons, and that is NOT a good thing!
You can put the tips on, but the lean condition may get you. If the dealer does it, and will still honor your warranty (in writing!), then you can take the chance, with knowledge you may end up with a top end job at some point depending upon circumstances. This is a worst-case scenario.
Good luck!
Steve Scott
