So far i've clocked 16000mi. on my 99 FXDX.The 103" (103hp,115lbs. TQ)motor easily pulls 6grand(often!)The cam(TW60)has a .560 lift and works the valves thru SE roller rockers.Maybe if this set lets go I'll try the S&S conversion,but not in any hurry. Hopes this helps.
it's one of those things, damned if you do and damned if you don't.
The main advantage is that you can run real big cams with them as they reverse the direction of rotation of the rear cam eliminating lobe to lobe interference.
If you use the stock cam plate, some are quiet and some are real noisy. It would be a good idea to use a Delkron cam plate if you use the gears.
We use the chains in most engines and have had no problems with them, but we modify them some.
Thanks guys, the tuner I've talked to says it will be another 5 years or so before people are upset with the chain drive setup. Not a big deal performance wise he claims but that the chain guides will wear out and the vast majority that don't maintian properly will suffer........who knows?