What does my sig have to do with this topic? Are you talking about my cars? Oh, that's right.. I must not know about suspension on a mustang because it's not what I drive.
Sleeve type coil overs do nothing other than allow for height adjustment, and unless you pair them with adjustable shocks, they're still a far cry from any well designed performance application coil over. It doesn't matter what brand those sleeve type coil overs are, they are just as good as any cheap ebay sleeve.. biggest difference is going to be spring rate/spring material and sleeve material.
I've dealt with plenty of coil overs, ranging from sleeve types to full blown circuit coil overs and even straight up, top of the line luxury coil overs. Have you ever ridden in a car with a quality coil over that was properly setup and balanced?
Any sleeve is going to be hardly comparable to a real coil over that allows height, dampening(rebound, compression and preload), as well as shock travel adjustment in really any performance aspect... yes even in drag racing.
So, really.. sleeve type coilovers, in general, are junk as I said. They don't do much for a car other than looks, a change in spring rate and simple height adjustment.
Sure, sleeve type coilovers work, and can get someone by with a street car, but you get what you pay for is essentially what it comes down to.. all from a performance aspect, of course.