Answer:
FHA Which is 30% of his gross monthly income.
I have seen FHA go as high a 34% of gross monthly income but that was with a larger down payment rather than the minimum of 3.5%.
With a Freddie/Fannie the maximum payment would be $1,188 PITI.
Freddie/Fannie will go to 36% of gross monthly income because of the 20% down payment. They would also go with a higher ratio with a larger down payment.
Explanation: