I just bought a 2000 RK and would like to add 12" mini apes. Can I get away with ALL the stock cables, lines and wires? Any advise would be appreciated.
No Ed, not with 12" apes. You will need new cables and wire extensions. I have 12's on my 01 Road King and just picked up a 9" ape for my Glide that is not "supposed" to need any cable/wire changes. Have not yet gotten around to putting them on. In short bigger/longer/taller bars = added length of everything (except your Johnson).
I second that. Go with 10" and you will not need new cables etc. Longer than 10" and yes you will be doing a lot more work and more money. Basically you need to know what fits you and if you need taller bars to feel comfortable you will just have to spend the cash.