I have Hamilton springs and they are nice. We have ran the hamilton springs to 950hp and 80+ lbs of boost in 02bigstrokins motor with great success. His truck gained over 100hp going from stock springs to hamiltons.
So Cal springs are very nice and come with new retainers which is nice and cuts down on valvetrain weight. They are also beehive springs which saves more weight and were designed by Guy and comp cams specifically around the needs of the dmax. Alot of guys run huge power with them.
You cant go wrong either way.