As far as I know they are ALL chasis dino's that measure to the rear wheels (never seen an independant engine dino test in a mag, but when the dino was especifically listed in the mags I havve seen here it was a normal rear-wheel dino).

But I believe they compensate the rear wheel horsepower for the driveline loss of HP by using a formula and hence the HP rating they give are an aproximation to SAE. Its not rear whell HP since like you say, 361HP rear wheel HP would be incredible.
Since they are compensated numbers I believe thats why magazine dino results are not perfectly accurate by themselves but rather used for comparison between tested models (not to mention that the same car's dino results can vary a bit form one day to another).
So thats why I was asking for more results, to have a broader perspective to see if many similar results would confirm that the 355HP power figure is a bit conservative. I believe the same same happened with Porsches X51 and X50 powerkits, they power rating was very conservative.

Usually I find that in the magazines (in spansih magazines they tend to do independant dinos in the tests) when I look at dino results they are a bit under factory specs, but the 997S has been so far 361HP, 358HP and 358HP which strikes me a bit odd since that is not usual, and didn't happen with the 996 for example. Also the acceleration numbers are more than you would expect from 355HP in the tests