Third ROC

Is it because the fuel system cannot keep up with the demand? Or is it that the K03 turbos cannot maintain that pressure?

If it is the turbos that are the limiting factor, can someone please explain in detail the theory behind it + turbo efficiency.

If it is the fuel system, then wouldn't an upgrade FPR, injectors, etc...allow us to run higher boost at high rpm's?

System_S4k

Guys with the K04's say the boost no longer tapers, but they are all looking for bigger injectors right now.

//scottInSoCal

as flow increases through a compressor, so does pressure ratio - up to a point. There are a number of factors that determine where the pressure ratio begins to fall off, including: compressor design, the properties of the fluid in the compressor (air, in this case), the temperature, the speed of sound, etc... The relationship between pressure ratio and air flow is the efficiency. Essentially, there is a point where the air flow through the compressor will become choked (no more can possibly flow through) - if you try to push it harder, no more air is going to come through, but your losses will continue to rise, thus reducing your pressure ratio.

PhoenixGTS

possible. Remember that the stock ECU only calls for what, 11 pounds of boost, and when you ask it for 15 the turbo is just not big enough to flow that kind of air above 5,500 rpm or so. Problem is that in order to make a bar or more of cool boost at 7,000 rpm, you need a turbo big enough that it is going to have more lag on the bottom (having twin turbos helps this a great deal as you can have two smaller units instead of one big one).