Well my 325's finally arrived from Montreal, Michele Knautz is great to deal with. Now I want to gain a couple of inches to go along with some generous fender trimming to get them to fit on my Stupid Duty. Right now I have 4" springs up front with about a 350lb/in rate if I put in a full length add-a-leaf it will go up to 400lb/in - how much stiffer will this be, my truck weighs in at 7070lbs.

Thanks
JP