JBrady

I am sorry but on what information do you make this claim? Let me explain how a MAF works. It measures actual mass air flow. This is the key component that the computer uses to determine fuel requirements. In a number of OBDII engines (such as the GM LS1/LS6) it is possible to blow through the MAF (with a turbo, supercharger or NOS) and the computer will compensate the fuel requirements up to the capacity of the fuel injectors (ignition timing is another subject). I do not have the specific programming details of the OBDII or earlier 1UZ-FEs but I will say that VERY few cars are programmed without a safety margin of at least 10% in fuel correction capacity.

Do not confuse the SRT HFI system (if by chance this is your reference). The SRT uses the stock MAF element in a larger diameter feed tube. This allow more mass flow for any given output of the MAF sensor. This requires a richening of the signal prior to the computer or a lean condition will definitely occur. With our cars using stock MAF componetry this condition is not a problem. Better flowing parts BEFORE the MAF will not create a problem. In the same way that a dirty air filter would be a restriction a better flowing part would just flow more air and the MAF would read it and instruct the ECU.

Subsequently , a better flowing exhaust system would reduce the residual exhaust gasses in the combustion chamber allowing more to flow into during the intake stroke. The combination of more A/F in the chambers (releasing more power upon ignition) with the reduction of pumping losses will create more power. The larger mass flow through the MAF will be compensated as above.

All of this ASSUMES that the modified part actually flows better than the stock parts. As Lee has learned just because an intake LOOKS like it will flow more does not mean that it will. That said, I have measured an increase in power with my intake mod as has Peter Scott at PlanetSoarer.com.

SCV8

MAF doesn't do much at hi revs; the eprom does that function,and you'll need more than a 10% accelleration shot down at lower revs to compensate for a big exhaust and intake.If only it were as simple.
You may be able and fool the ECM by playing with resistors in the coolant temp circuit,however,as this will advance the timing a bit as well,might be worth a try.
The SRT intake wont flow any more than a stock tube if this part goes between the MAF and the throttle body;the laws of physics restrict a section to flowing only to the limits of the restrictions placed at either end,if that part is other than what I just described,sorry man,I've never seen a SRT hfi.

JBrady

SCV8, I think you are confusing the MAF (mass aif flow) sensor with the o2 (oxygen sensors). The o2 sensors on pre-OBD (on board diagnostics) I and II were only used during the closed loop mode and not during WOT (wide open throttle). The MAF on the otherhand continuously measures the air flow in MASS. This, as I said above, is the KEY component in determining the actual air MASS that is flowing into the engine. I gave support info above so read there for a refresher.

You mentioned the eprom (electronically programmable read only memory) which is only one type of chip within the ECU. As a car is driven the ECU is designed to adapt to driving style, conditions (such as octane and igition retard) to prevent detonation or any other adverse operating conditions due to climate, maintenance or other outside influences.

Now, when you increase MASS air flow through the engine the various sensors (of which the MAF is key) tell the system to increase fuel delivery and will due so up to the limits of the factory programming. I guarantee the Toyota engineers have included a fair amount of safety ABOVE the stock flow. How much more??? Hard to say but 10% is definite and that is 30hp range on top of our standard output.

Now, this is assuming the STOCK MAF is unadulterated. If your cold air system causes turbulence in the MAF you could have a problem. Higher flowing exhaust components are NOT a problem.

As far as the SRT HFI, I detailed that above, SRT removes the stock ELEMENT from the stock MAF housing and places it in a larger diameter tube. They provide a modified signal to compensate for the change in reading vs. actual flow that the MAF signals to the ECU.

Fear not, a good intake and modified exhaust will be compensated for just fine under the above parameters. Cheers