guys, guys. there is no free lunch. you won't get more HP without more fuel, and you cant' have a power enhancement without putting your factory warranty at risk. period end of story, although its true that this box is a low profile box and one of the least "risky" in that sense.
So you want more HP than stock? then you have to at more fuel than stock.
If this box does not raise fuel pressure above stock maximum then it does not deliver HP above stock maximum values. And it is not a timing box unless it hooks up to the injectors. Since it only hooks up to the pressure port it is a pressure only box.
now then, its true that the HPCR itself is not kept at 1600 bar all the time (stock) -- actual pressure is set by the ECM on the fly and reponds to commands associated with various conditions according to ECM programming. So indeed, you can raise rail pressure above stock levels without going over the maximum of 1600 bar and yes you should certainly get a seat-o-pants improvement in responsiveness if you do that. But you are not increasing peak HP -- only changing the shape of torque curve (making power "come in earlier"). Such a truck will dyno with no more HP than stock.
conclusions:
1. the box plugs into the pressure port and not the injectors. Therefore it is a pressure only box. no timing. Therefore it adds fuel above stock levels by raising rail pressure over stock levels.
2. the box can cannot give any HP increase over 305 HP without raising rail pressure above maximum stock levels.
3. the box claims torque and HP increases: these absolutely cannot be above stock (peak) levels! 90 HP increase and 120 ft lbs of torque compared with what? probably compared with a certain lower-end portion of the torque and HP curves -- certainly NOT the peak levels.
4. "more uniform pressure" probably means it maintains near-peak (1600 bar) pressure all the time. Thats more low-end HP than stock, and probably slightly better fuel atomization. So claims of mph improvements are probably valid -- if you want your HPCR to sustain 1600 bar with 100% duty cycle.
5. max EGT is probably not an issue because max stock HP levels are never exceeded.
6. The Dr. performance claims are misleading in the sense that he is claiming HP and torque increases. While the rest of the fueling box world compares their boxes to stock PEAK levels, this one compares to stock NON-PEAK levels. So you only get a responsiveness and drivabillity change, and no peak output change.
7. The reason this box does not raise warranty concerns at the named dealership is because it does not make the engine deliver any greater peak power than stock. However, the dealership is not the arbitor of warranty claims, and in the event of major engine or driveline failure, you 'd have an fun time on your hands.
8. If your fuel rail actually failed, you will have a very hard time convincing DC that an elevated full pressure rail was not the cause. In that sense, this box is no different than other pressure boxes out there, except that this one won't give you peak HP any higher than stock.
So we should be careful not to discredit this box for what it does, but we should indeed point out misleading claims.
But I wonder how it would perform stacked with a TST box!