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try RC engineering's website, they have some calculations. (I think it's rceng.com )
You'll need to know what your current injectors flow at in cc/min.
You'll need to approximate how much HP you'll be making to determine how much more cc/min you'll need from your injectors. Expect at least an additional 10 - 15 HP per/psi, I recently dyno'd my 4age, stock it had 112 HP, at 7 psi it had 195-200 HP, so probably go with 15 HP per/psi.
edit : Almost forgot this step, calculate how much cc/min injectors you'll need for your estimated HP using the provided formula, use a BSFC of 0.6 for safety, richer is safer.
So their should be a formula on their for calculating how much fuel pressure you'll need to squeeze X cc/min from your injectors.
Once you know the fuel pressure, let's say it's 80 psi for example and stock is 42.5 psi, then you'll need approx. 40 psi additional rail pressure, if your running 5 psi of boost, then 40/5 = 8, so you'll need an 8:1 rising rate regulator (FMU), since an RRR or FMU rise X psi per 1 psi of boost.
With both the fixed rate regulator and the FMU you'll be able to tune it much better so don't get rid of the regulator you already have.
One question tho, what year tercel do you have? Cause the '95 and newer have a returnless fuel system, so I don' t know how you'd go about incorporating this stuff.
Neil
