Just put I a set of 551 S&S cams in my '10 RK and my mileage dropped from 40 mpg to 27 mpg. I hope that a dyno tune scheduled for tomorrow will help improve mileage. The improvement in low end torque is well worth it and I really don't mind the extra money spent on fuel but having to stop every 100 miles is a pita. Wonder if this is normal? Guess I'll find out tomorrow. BTW , I didn't install a new map as I didn't find one that matched my minor build.

 

Nope. Tune should set you up. You will need a couple MPG sacrifice for the added performance as I lost 2-3 mpg when I did mine (37-38 mpg all around - 39-40 on highway). You can lean the tune out but then why put in the cams. I have my cruise range leaned but have it more rich in the acceleration range for performance. Now all I need to do is not twist the wick so much.

 

I put the 551's in my 2010 ultra when I did a 103 upgrade and I still get in the low 40's overall. Also using a FP3 programmer and no cat head pipe.