So what the reason behind the different elbows on thottle/idle cables? So I have 45degree on my 89 fxstc with the stock buckhorn. If I go to an ape, do I need to not only increase length or weather or not to go to a 90 degree? what factors are taken place when going 45 or 90? does it even F-ng matter?

 

You will have less binding on the cable pulling it past a 45° bend than you would pulling it past a 90° bend.
That said you can get your cables to follow your bars better with a 90° bend.
I've been running Barnett cables with 90° bends for years without any problems.