I've always used Wolff springs, because they offer quantity discounts for mag springs. They run @$5 each if you get the "10 pack." I use the +5% version. I've never tried the +10% version.
I run the Wolff +10% Extra Power Magazine Springs in my .45 Witness Magazines, which are very similar/same as Cz97B Magazines. In most 9mm Pistol Magazines, the Wolff +5% Extra Power Springs run best.

I did try Wolff +10% Magazine Springs in one other set of 9mm Handgun Double Column Magazines, and while not a total disaster, it took a couple of years for those Springs to wear in properly, even with regular use. I won't do that again!
