Another lowering question.
 

Gents I would like to lower only the rear of my vehicle it looks like a jacked up 1970's GTO. Can I do this without doing the front? Also on my 87 would it be the two bolts as described in Waynes 101? Thanks:cool:

The correct way to get more than a quarter inch to half inch is to re-index the torsion bars. By just tweaking the bolts you describe, you are probably just going to throw off the alignment and corner balance and not get any significant lowering at all. Same with the other car as well (assuming they have stock spring plates and not aftermarket adjustables).

Thanks Tony, I need at least half an inch from what I have measured.

The 911 handles best with a 1-1.5 degree nose down rake.

Measure at the door sill with an angle finder or a tube and water and some math.

Bklyn,
Porsche changed over to the two piece trailing arms to make it simpler to make minor adjustments to the rear height and corner balancing.
If you only need to lower your car less than one inch, by all means use the adjustment provided.
Keep in mind the affect upon the corner balance weight and alignment.
Using a level surface get an accurate beginning height of the right and left side.
Chances are they are not exactly the same.
Lower both sides to the desired height. Drive the car around the block, then recheck the new height.
Make any corrections as needed. Back around the block and recheck.
If you move both sides exactly the same you may not have affected your corner balance.
I, however, recommend you have the corner balance and alignment checked by a knowledgeable Porsche alignment shop. It is after all a twenty plus year old car.
You may choose to pull the torsion bars and re-index if you find yourself to be one of the anal Porsche owners.