If you plan on dropping the rear only an inch or so, then you should only remove about 1/8" from the frame. I removed 1/4"+ and had the rear drop just over 3". I had to shave the fender and modify my Danny Gray in order to make it fit.
I have this combination. First I love the seat, an as far as I know it really is the only seat that works perfect with the T-mod. I got two inches out of my T-mod and it look awesome. Here are detailed instructions on preforming the mod. I also have comparison photos on this thread. Several other members have used my instructions and love, they came out perfect. http://www.furyforums.com/forum/fury-diy-area/8672-t-mod-variation.html
I think I would rather get the Low & Mean shorter spring but then you would have to pay someone to install it. Don't have a 20 ton press laying around.
I think that was called a redneck press & I wouldn't want to attempt it ! Daryl at VTX-treme is working on a shock & lower spring combo that when he's done I'll be switching my stock shock and Lowered spring.
From Daryl when I sent him a stock spring for mock up. If I remember right he said it would be about now when the 1st one is ready to test.
Edit ( Just got off the phone with Daryl & he said the 1st one should be to him any time and the 2nd one is mine around the beginning of the year . He will do one run and put it up on his website , if we like it and they sell he will go from there but is 100% in for at least 1 run ! )
Sorry didn't see your post. Daryl could explain better the difference but I know it is a lower'd spring & shock combo that is engineer'd to work with the VTX-treme products for the Fury. The spring will be designed and built with the lower rear end and stretched front in mind along with the shock. As far as specific specs on the difference of a spring used the way it was designed and one shaved would be one of those VTX-treme questions