Looking for engine smoothness comparison between twin cam and m8 at cruising and upper rpms Thanks in advance

 

M8 is a much smoother engine at idle and on Hwy.

 

Definitely notice much less vibration on M8.

 

Depends what model you are comparing.....If you are comparing a twin cam touring to a M8 softail, then the twinkie is smoother.

 

My bad sorry I am comparing twin cam heritage to a m8 heritage

 

The M8 is a much much better package and the engine is way better too.

 

Agree. The M8 Heritage has a great suspension and motor upgrade. Works very well for 1-up riding and touring. Not so great for 2-up, however. The rigid mount engine gives more vibration at higher RPMs than a touring model. My BIL (40-year HD rider) loves his M8 Street Glide (compared to his Twin Cam) and I find that it's smoother at highway speeds than my '18 Heritage.