IMO: from my personal experience with the crap stock leaf springs fr(Broken front hook) I would purchase the alcan. If you need to install a new stock leaf it will cost you at least $200 for 1 side! Plus $165 plus the shims puts you a little closer.
I am assuming that it is roughly $300 for a set of springs plus shipping?
Do they come with military wrapped ends?
Someone said around $400 shipped, so yeah. I'm probably done modding, but if I do any more mods to the X (might not keep it past next year...long story...anyway...), it's going to be a) snork if it ever comes out, and b) new springs in the back. I was going to go with Alcan, however, this 3-leaf add on seems like a decent option at half the price of the Alcans. I mostly wanted a new pack because I wanted a significantly more stiff rear end and not just a lift.