Maybe peak, but that doesn't tell much of the story. Look at your curves again!
You made almost 30rwhp from 4800rpm to redline, and 20rwhp at 3400rpm from a much quicker spoolup. Noticeable gains from 2800rpm to redline, serious area under the curve added on the HP side.
On the torque side at 5200rpm and higher you picked up 25ft-lbs, no wonder you need more fuel!! Substantial gains from 2800rpm and up.
Once again proving, a good exhaust system is the best bang for your buck on the Z turbo motors, and in general, most turbo motors.