I have a 2008 Road King Classic with 42,000 miles (bought new in April 2008, I am only owner and rider). I am considering an engine upgrade and would like to hear opinions on whether to go with the S & S 106ci kit with EZ start cams (either 551 or or 583) or the Harley Davidson 103 upgrade with SE 255 cams. My bike is a 96ci Road King Classic with Rinehart true duals, a stage 1 ac, and a power commander III, lowered at the rear with the HD lowering kit. I have been reading extensively on this forum and others, so I know that are other combinations and cams, but I am inclined to limit myself to these two choices. I have about $2000 to spend, plus or minus a few hundred, and I will pay a pro to do the install, because it is more than I want to handle. I have estimates for complete install (parts and labor) for the 106 kit for $2300 (including power commander custom map), and for the HD 103 kit for 2000 (not including power commander map or dyno tuning - which I will have to get elsewhere -and with manual compression releases and required machining of stock heads included -- not needed for the 106 if I use the S & S EZ start cam) I am looking for improved low to midrange acceleration and power-- for example, I want the bike to jump when I twist the throttle in 6th gear when going 70 to 75 mph, so I can accelerate quickly another 10 mph or so. I generally ride 1 up with a light load. I also want improved pick up (torque) off the start. I usually ride on the highway at highway speeds above 60 mph, at sea level, in non-mountainous terrain, though I want hill climbing power if possible). I want to use stock heads, at this point, and limit use of any other parts not included in these kits, if possible (need for recommended extra parts would be relevant in deciding which kit to go with). My sense from reading is that both of these kits are good, and will be a big upgrade in power, so the basic question is this: Does the 106 ci kit provide enough additional torque and hp (and reliability) where I ride to be worth the extra money? To put it another way, is it better, or about the same? Secondary questions: Any hidden disasters in either? And finally: Any thoughts on the cam choice: S & S EZ start 551 or 583? HD 255 or 253 or 254E? Thanks for any assistance.