That is a difference of 31 horsepower and 28 pound-feet of torque at the wheels. What you see here is the difference between a canned one size fits all tuned that is resold and a tuner that is capable of taking an individual approach per car and its modifications.
Now whomever the tuner is for MHP this time (and there have been a few) likely could approach similar gains with a custom dyno tune but those are more expensive as they take more time. What MHP is doing is essentially acting as a middle-man reselling a canned tune. Why pay more for less? With Eurocharged on the M156/C63 AMG you can pay less for more. The proof is below.
The car also gained 3/10's in the 1/4 mile and 3 miles per hour of trap speed which those familiar with drag racing rules of thumb will see correlate with the dyno gains in the graph. The timeslip is also included below the graph.