How are you planning on using the car, street, dual purpose, strip only? If you're considering cal-tracs, I'll assume dual purpose. Do you have a budget you have to stick to?
The Cal-tracs with mono-leafs are a nice set up. I don't know that they are any "quicker" than a well set up set of SS springs, but they do look trick and are a bit lighter in weight. They will tend to be a bit more pricey
Super stocks are a proven performer. With a little bit of tuning, they can be awesome. Prices are not too expensive but they will require new hangers and extended length shocks. Their increased leaf count means they will ride a bit rougher and be quite a bit heavier than the cal-trac mono set up.
XHD are a fair all around performer on the street but will not stand up well to regular drag strip use. I've installed several sets of these on my cars over the years and I've never noticed any excessive sagging issues on my cars, but they not designed to provide lift over stock and I expected them to slightly settle. Most new leafs will have a slight additional arc when new and will set into a position after some use. The better the spring, the less this settling amount will be. If your pushing a lot of engine torque through these and launch on a sticky track, you will need a pinion snubber to control the motion. These will probably be the most budget concious set up of the bunch.
