I am a tall fighter 6.6ft and I can say my largest weak point is body ... If you slip inside and hammer at the gut youl have him but watch your...
If you have a Droid phone you can get a list of all of the p90x workouts ...aps called 90droid I think :)
I had a similar experience a good while back with a friend i was sparing with. i slipped his hook and landed a good shot to his gut and he went...
I used to be only 134lb and wanted to gain and what worked great for me was adding a gallon of whole milk a day to my diet. i gained around 4lbs...