[WILLIS3251]

Hi - one comment I've heard about the new M-8 stage 4 kits is that the cams are very top end, low-mid range is vey much like the stock motor??? The stage IV S.E. cams have to meet EPA standards - so the valve timing is not optimal. I've got the 110 cu stage IV kit in my 2013 softail. I took the 259E cams out - went with a set of the Crane/S&S rocket cams - much better throttle response and low- mid range. top end made more power too. all-around better running. shop the after -market for a different M-8 cam? S&S and Andrews have new grinds. good luck!

 

[WILLIS3251]

The S.E. kit hardware (pistons, EFI, jugs) are good quality - as Therm said - it 's the MOCO tuning and cam timing. changing the cams and installing a custom tune on my SERT made a huge difference in the way the bike runs. Not just power, but idle, and throttle response at slow speed. the original tune w/the 259E cams had a bad habit of stalling in a hard lurch (almost throw you off the seat!) when leaving a stop if the motor wasn't warmed up!!!:duh2:

 

[WILLIS3251]

HI - different exhaust on a "modified" motor can be a big change in motor output. I've had a pipe change be good for 18-20 HP!!
and yes - you should feel a serious difference going from 106/106 to 126/133?? I've run a bike at almost exactly both of those sets of numbers - the performance delta is huge. My stg IV 103 was in the 109/109 range and my current 110 cu is running in the 126/130's. Yeah - when you hit the 2500 - 3000 RPM point- it's like you hit the nitrous button!!