I would be careful running a tune and boost max in line. It seems like its just faking the ECU into thinking the boost and other sensors are reading lower than they really are. I was working with a guy on the Jeep diesel forum who was running a Diablosport Powerpuck in combination with a hot custom tune he had gotten and he experienced a boost runaway of sorts. Basically the Powerpuck was acting as a resistor in between the MAP sensor and the ECU so that the ecu was seeing a lower voltage than the MAP sensor was actually outputting, and therefore trying to increase boost to hit its target. The problem was, the tune was asking for more boost than stock, and the powerpuck was faking the signal, and so the two combined were basically demanding more boost than the MAP sensor could read(3 Bar or 29 psi boost) and so the ECU just kept trying more and more to increase boost. The MAP sensor pegged at 5V output but the powerpuck was reducing it to something lower than what the ECU was looking for from the boost maps. Guy said he hit almost 38 psi when the hot tune alone called for 23 psi.
Luckily this was a diesel so the AFR doesnt matter, but the consequences could be much worse in a gas engine.
