They were already on the bike when I bought it, so I don't have the original paperwork that came with them.  I have heard everything from the stock 91mm to 125mm.  Anyone know for sure?  Thanks in advance!

I used the 5.5" (140mm) generic figure on the Progressive sheet enclosed with the springs.  Has worked OK for me for over 130k miles on my 97 and 02 GSs, same set of springs.

Thanks Jack!  Are you running 20 weight oil and 3/4" spacers in them as well?   That seems pretty popular 'round these parts.

I used the Progressive recommended 3/4" spacers and left in the stock 10 weight oil when I transferred the springs to my 02 GS at 4k miles which has over 98k on it now, more than stiff enough for me.  I put 1 1/4" rear lowering links on at 37k miles back in 5-06 which stiffened the rear a bit due to the geometry change and it all felt well balanced to me that way.  I know others changed to 15 or 20 weight oil but think that is more with the straight rate springs set for rider weight which are now more popular here than the stiffer Progressive springs.  Just replaced my worn out stock rear shock last month with a low mileage eBay stock one and all is good again, feels nicely balanced to me again.

Oil level is measured with the springs removed and the fork compressed.

+1

Good info.  Thanks guys!