Originally Posted by Baron
I was noticing the same thing. I would have to wear an XL in this shirt and I don't think I'm all that big a guy (5' 11" 170). Yesterday I tried on some BOO shirts in size L and they stretched tight across my chest. It seems like they could have more distance between the sizes.
You would probably take a large. I was the fit model for the medium, and I am 5'11" and just under 165 lbs, but my frame is pretty long, lean, and rather narrow. If you want a more relaxed fit, you probably want to go for the XL.
The sizing for the shirt follows European sizing (not for the more conservative brands.) A medium fits a lean 48Eu (me), and the XL is about a 52 Eu, and is meant to be fairly fitted.
I hope that helps!