I have a JDM B16a SiR II motor. And I am planning on better fuel management. So here what i came up with.

450 cc Injectors
VAFC
Walbro 250 lph Fuel Pump

You think its better to change the fuel pump than to use the stock fuel pump? And will my gas mileage be shitty?

 

If you already have it you should put it in you dont wanna run lean on the top of 7k and blow up . I doubt there will be any difference in gas mileage if you install the fuel pump alone considering all fuel that is send to injectors is returned .

 

When you have it just put it in your car dude. That will not effect your fuel pressure at all thats the job of the Fuel pressure regulator. So dont worry and just put the fuel pump it has more advantages than disadvnatages

 

Think of it this way...

Your fuel system is a circle, from your tank through your regulator, through your fuel rail back to your tank. Much like how the city runs water pipes down a street. Your injectors are like houses, they use fuel when they need it. When they do this fuel gets taken out of the system and get replaced by the tank, like a resevoir for a city. The pressure regulater or fuel management unit/system makes sure the fuel line stays at pressure.

From this explanation you can see that if you increase the injector size, more fuel will be removed from the line and compensated with pump. But up to a point the pump will have far to much stress on it for high levels of compensation. This will result in destroying the pump.

also for under a 100 bucks you know your covered up to 500hp, i think it's pretty close to a no brainer.