Stock Fuel pressure

[jimberg]

You really don't want less pressure than stock pressure. What you set it to depends on how much horsepower your engine can put out and what size injectors you have. The general rule of thumb is that you need .5 lbs of fuel per hour for each HP. 19 lb injectors will deliver 19 lbs/hour at 39psi. This means that each injector could support up to 38 HP. Multiply that by 8 and you get 304 HP. This is obviously just a rough estimate since the .5 is just an average. You really need to put it on a dyno with a wideband O2 sensor to see what your actual fuel requirements are.

If you want to calculate the rating of your fuel injector at a higher fuel pressure, you use this formula:

Sqrt( New Fuel Pressure/ 39 ) * injector rating

If you want to figure out what fuel pressure to run to meet a specific rating, you use this formula:

(39 * target injector size ^ 2) / injector rating ^ 2

Injector rating would be 19 in your case.