I got my stonguard installed thursday, and it looks really good on the blue. You can't tell you have it on until you are right up on it. I did some fast checking, and so far, it looks like it was done well. I see some tiny air bubbles that the guy didn't see, but i could get rid of them easily. The only problem was that i didn't have time to fix my paint chips before i stonguard it. But since i just purchased the blue, i didn't have that many.

Since the product was a gift, i got a great bargin...

 

I think its a foregone conclusion that StonGard makes the better kits as far as protection goes, but they are more expensive for several reasons.

StonGard designs the kits to have as few seams or edges showing as possible,
Point 1 where Xpel designs the kits to be chopped up so that more material can be nestled in to a given size sheet of Scotchcal.
Point 2 Xpel also designs the kits with relief cuts and doesn't wrap the leading edge of the hoods. Point 3 .

Remember in grade school the map of the world on the wall? Remember how it looked like sombody had peeled an orange and layed the skin out flat with all those cuts in the oceans?
If you cut out that map, you could wrap it around a beach ball without any wrinkles( but lots of seams). That's Xpel's design. The kits are easier to install and cost less.

StonGard kits are designed to be stretched in those areas where others leave the cuts. The end result is a better looking install that is easier to take care of, with fewer seams and edges to worry about getting caught in a wash mit during cleaning.

These reasons also mean the StonGard kit will take probably twice as long to install, and since they are using more material to make the kits, cost more to begin with.

As far as leaving any marks when the film is removed, as long as the paint is factory or a properly done and cured repaint, there will be no harm done. If you have lots of fine scratches or swirl marks in a few years, then if you remove the film, the protected area will not have these marks. It will look like new so there will be a difference if you have scratches on the unprotected areas.

The headlight issue is still a touchy subject. I have seen an S2000 have these headlight issues without ever having StonGard on the lens. The problem is called "crazing" and it appears to be somewhat common on polycorbonite plastics, more so in the aviation industry than automotive. Since examples are tuning up of this problem on headlights that never had StonGard on them, I would have to rule this out as an explanation. I don't agree with the way the problem was first addressed at StonGard regarding the crazed headlights that have occured, it could have been handled better.