What's more important or what's the advantage of upper or lower adjustable control arms? Done my due diligence but got no where.

 

if you're only going to get 4.... get front lowers and rear uppers. They are what you need to correct castor angle and help driveline and driving.

 

They do the same thing.

Front Lowers -
Lengthen to increase caster / lower pinion
Shorten to decrease caster / raise pinion

Front uppers -
Shorten to increase caster / lower pinion
Lengthen to decrease caster / raise pinion

Front lowers will generally have a greater range of adjustability than uppers. Uppers may or may not adjust short enough to get the caster where you want it, so lowers are the better choice if you only get one set.

 

Is this something I need or it just makes it easier to align? Does it handle on the road better, off road, more travel?

 

It is preference and budget. As you lift higher, the castor gets lower and lower, causing flighty handling, and the steering angles may be off, causing bumpsteer. (it will wander more and/or jerk to one side when you hit any bumps in the road, etc. How bad or how much, depends on any number of variables).

Stock caster is around 4deg. Post lift, depending on height, it could to be in the 2-3deg range? Many people like to run somewhere in the 4-6deg range after a lift.

With the stock control arms, castor can NOT be adjusted. With the stock balljoints/axle ends, the camber can NOT be adjusted. So don't pay a shop for an alignment they can NOT do.

 

Oh, good to know. Thanks, its making more sense now