You'll find some more info on the stages of the engines in this forum (DIY)... https://www.hdforums.com/forumid_248/tt.htm

 

The mileage should not vary greatly, some have even seen improvements when done right. The problem comes in when you "test" out the new found power. It's hard not to.

Intake, ehaust and fuel enrichment make the engine breathe easier and can add 8 - 10 HP.

 

DCRANER:

Before installing the dbl barrel 16 gauge shotguns, make sure you hear them on someone's bike!!! I had them on my '03 Heritage and, while I liked them for riding around town, they became numbingly deafening while on long trips. My right ear would ring for a day or two after a full day's ride. They sound great, don't get me wrong, and are probably the best sounding pipes I have heard on the bike -- low, open, with a mean bark when you get on it. I've compared them in side-by-side SE II's, and the 16 gauge dbl barrels are louder! In fact, when riding in a group, no one would ride to my right -- or very close behind me. It was fun, however, to ride through parking lots and set off all the car alarms.... And going under bridges? Wow, you could make some noise.

Just didn't want you to be disappointed.

 

I have an ’07 FLHR with SE II mufflers and would like to installed my newly purchased AN BS stage 1 air kit. Since I’ve got an opportunity to get a free download (due to bulletin), what curve would you recommend I request to compliment the air kit and help keep my ride AFR in check?

Thanks,

Em …