Results from moving bar on birdcage

If you move the top left bar forward or backwards from the center hole on the birdcage what is the result? If it’s forward it take index out at droop but what happens when it’s a below droop?

I'd assume that, for a precise answer, you'd have to include if you are using the same length link and moving it forward/back the same amount on both the chassis and birdcage, or are altering the link length to connect it to a different hole?

Same length and only moving on birdcage

Assuming I understand you correctly, I'd say:

A) Don't do that.
B) You'd significantly change your left side wheel base
C) You'd significantly change your LR spring/shock center to center not only statically, but at full droop, and every point in between.

It may sound trivial or sarcastic (and that is by no means my intent), but a lot can be learned about our rear suspension with the car up on jackstands, using nothing more than a tape measure, plumbob, and angle finder. If you don't have one already, put together a LR ride height stick (set at the C-C of your LR shock/spring at "ride height" or your manufacturers static distance) and measure things like the trail/lead of your LR ("wheelbase"), link angles, etc. Then let the suspension hang to "full droop" (obviously now supported by the chain or limiter on the LR), and see how those same things changed. Measure or check your C-C of the shock/spring at full droop (you need to know that to accurately set your droop load), then move a link or links around and see how that full droop C-C changes.

You can fill up a few pages in a notebook pretty quickly by messing around like that. It'll help you make more educated adjustments at the track, too.

If ur goal is zero indexing, youll have to move both bars......top forward, bottom rearward!

This is usually done to take out drive on lower hp classes!