Ok I have a set of frpp lowering springs (1.5") on my car, I just installed a UMI adj. upper control arm and j & m extreme lower control arms, when I lowered the car back down the ride height in the rear shifted up, it looks like it is setting on stock springs again, would this be just the adjustment on the upper control arm to bring the rear back down again.

 

Nope, that sets pinion angle.
Nothing compensates for spring height.
Nothing except more weight.
Did you tighten all hardware at ride height?
If not your bushings are in an EXTREME bind.
Thats whats keeping the rear end up...
Loosen everything you fiddled with and retighten
at ride height instead of tires hanging from the springs...

FRPPs for the GT wont drop the V6 1.5"...

 

Thats why I went with the Eibach Pro- kit because of the weight differences the diff. springs accomodate.

 

Ok the passenger side is setting way better, that seems to be were it should be, the driver's side is the one setting up.

 

Are the pig tails in the proper orientation?
Are both springs installed right side up?

 

The springs are correctly on, the car was level before the new parts install, not sure what you mean by pigtails though. Nevermind on the pigtails I know what you mean.

 

All I did when I replaced the parts was jack the car up, support the rear axle and swapped out the control arms, oh and tightened up the adjustments on the panhard bar, so I don't think the springs would of shifted at all. I went out earlier and looked and they seem to be in correctly. The passenger side sets at 27 5/8" and the driver side is at 28 1/8", the measurement was from ground to the bottom of the fender.

 

tighten hardware at ride height to fix problem...