Both companies offer setups that are good for one, the other, and with minor parts swapping... both.
FWIW, I'd pass on the 5-link. It's just a reangle job on the uppers and a PHB. It doesn't do enough improvement for the class changes it brings you into if you do much sanctioned racing.
Maximum Motorsports and Griggs Racing both offer spectacular road race packages and drag oriented packages. If you select a full-house complete package from either and buy a couple extra sets of springs and sway bars you should be able to tune the car to just about any type of racing but you still end up being tossed into modified classes a lot.
I run the Maximum Max Grip box and it's put me in the same racing classes as some pretty hot rides but the handling and grip are insane... especially past the limit.