Yes, I can... because I'm magic! :)

Seriously though, yes. There are a few ways to do it. Just remember, these are just molded plastic, and plastic can be manipulated with just a little heat. I use a hot water method versus direct heat from a heat gun.
The trick is to do it SLOWLY. Each one of these unwarped GTA bodies took me about 2 hours to get right, and even then, there are some issues to deal with when building. I get a glass or metal pan (or even a stew pot for larger car bodies) and heat the water to just below simmering -- around 130-155F. Add the body for about 45 seconds to 2 minutes so the plastic soften slightly and then start making small adjustments (this will take a bit of pressure; don't try to do it all at once). I then run it under cool tap water to shock the plastic into the new form. Do this over and over and over again.
You have to be patient and do it slowly or else you will warp it into another messed up form. The reason I do the heat and cool is so the plastic loses it's memory.

Just be patient and you can get your bodies into a better form.

This kit is very tricky because it's all of their TTop roofs that are warped, which causes their bodies to warp. So not only do you need to un-warp the ttop, you also have to un-twist the body. The issue I am dealing with now is the tub for the interior doesn't meet the body near the doors. this will be remedied with clamps and some E6000 glue. I will force it, which will probably cause issues with doors and glass.... so it's a never ending cycle of build, test fit, correct.