The SVT doesn't have a replaceable 'chip' we have to use a flash tool to load a new program into the computer. Works the same way basically.
The two brands I know of are SCT(Xcalibrater, Xcalibrater II) and Diablo (Predator) both are good tools, custom tunes are offered by quite a few places.
I personally have the SCT Xcal2, custom tuned by Wayne at Hypnotic Illusions Automotive. He has a forum on this site. I like it very much. I hear all good things about the predator as well.