As promised here are some pictures of my rear fenders and the cuts I'm making on them. The rims are off a  944 Turbo , 16 x 8's with 225/50-16's.

This is the good side . I actually cut the drivers side first and experimented with that side first.

Drivers side, I have to replace this quarter panel due to the extensive damage so I figured I couldn't mess it up too bad compared to what it was.
I have at least 3/8 inch clearance between tire and fender. The next step will be to weld material in to fill in the gaps. The challanging part will be making a nice contour or transition between the cut panels. The area that needs to be pulled out the most is the trailing edge of the fender opening due to the fender having a slight taper in towards the back of the car.

Just a few more shots, I'll post more as the body work gets done.

  Here is a comparison between a 100# spring (left) & a 180# spring.

100 # SPRING 180 # SPRING
Free height 13.75 13.25
Inside dia. 3.25 3.40
Spring dia. .440 .440
Outside dia. (ref) 4.13 4.28
All dimensions are inches