I'm about 6' and 200lb ish. I could probably stand to lose 10lb so I'm probably a similar build to you. I really don't feel I (or you for that matter) have hit my max potential. It's all about eating BIG and lifting BIG.

What is your diet like? How many cals do you consume? Is it consistent?

What is your routine like? Do you do squats, deads, bench, and military press? (if not...you should!)

I would turn to diet and exercise changes before going the PH route but that's just me.

IW