It looks like it could be a good deal for someone planning to pay a dealer to tear down a good motor for performance upgrades. You are looking at close to $5K out of the pocket in parts and labor for the dealer to install a 107 kit. I believe you could have a dealer install the 120ST and leave you with a 103 that could be sold to cover some of the cost for the same or less out of the pocket. You would have a brand new motor that may be more reliable than one that has been modded. When you bring back a dealer modded motor they're going to try and put the blame on the parts and the part supplier is going to put the blame on the installer. Who's going to be the looser?
Billy

 

My 2016 Road Glide with 120R. Screaming eagle super tuner, and SE Billet air flow, 58mm throttle body and injectors, heavy duty clutch, D&D Boarzilla pipes. Dyno at 100 mi to get the tuning right. 142hp without killing it. 1200 mi on now. will dyno over the winter to get some new #s. Bike is crazy fast! Whole setup, installed on new bike, $9400

 

I've ran with the 120 and yes it will walk away from my 103 cammed scoot, but, they're plenty other options out there smoke that 120. Just depends whether you want to pay HD prices and labor or go another route.