Damn, this one strikes home!

For those who aren't familiar with the dilemma, if you're bulked in the right way, you will need extra room in the neck and shoulders but not in the body. So if you find a shirt with a 19" or 20" neck, it may fit well in the shoulders, but will fit your body like a tent. If you find a shirt that is tapered enough for your body, the neck will be at least two inches too tight. (And if you're tall and need anything longer than a 36" sleeve, you're really screwed.)

Arrow used to make a line of shirts called Brigade which were athletic cut, but they maxed out, I believe, at a 17" or 18" neck. It's been a while since I've seen them, so I'm not sure if they're still made.

Zoolander is right - the only solution if you're bulked is to go with custom made shirts. I've used an independent shirtmaker who does good work at a reasonable price, and found that independents are more reasonable and better at tailoring shirts than the so-called custom chain stores. (The guy I use makes one shirt for you to try, makes any corrections, and then makes the rest of the order. Most chain stores will make the entire order at once and, if they do not fit, you're screwed.)