I've added the extended Stainless steel brake lines in the rear and my brakes have firmed up quite a bit. Enough where I've had to adjust my braking habits to the lighter side. I highle recommend them. Stillen sells them as well as Pro-Comp which are the ones sold by an unnamed company with they're lift kit.
Also you can go just about anywhere that sells SS brake lines and select length and type of fitting for ends.(brake lines have standardized ends)