My hair is extra super thick. I got a deva cut and that helped with the volume a lot. She did not thin my hair or cut it with a razor, but she did kind of layer it so that all the volume is not in one area, which has helped it to look less poofy.
I have heard lots of horror stories about cuts with thinning shears, so if you are going to do that I would look for someone who specializes in that, although I think that you could probably achieve the same look with just a really good cut.
3B with some 3a. Fell off but am now back on the CG bandwagon and looking for my HG products.