550 injectors Options

[lawngsx]

I am currently running an EVO III B16g and the stock 450s, uip, GM MAF-T, 3" exhaust, Walbro 255, etc. Well as you may have guessed, I have maxed out the 450s and am now looking for what to upgrade to. The options I'm looking at are 550s and 680s from either FIC or PTE. I'd like to stick with the same turbo for a while, even after a built motor goes in. Now the question is, will I max out the 550s with this turbo (running ~25psi)? I have a friend here at school that has a B16g, FMIC, etc and 550s and is convinced he has maxed them out at ~22psi.

Also, if I were to go with the 6xx injectors, would I need a burned chip to compensate for the idle or would I be able to iron things out with the MAF-T?

[wortdog]

all this dsm tuning stuff is so beyond my meager understanding...
720's be ok for a frank3 and a 20g?
How much hp can a stock 4g63 bottom end take?

You seem to do well enough at tuning these things from results.

Here's another way to look at it:

Marcus's car with 450's and a 14b put roughly 325hp to the ground. An EVO III 16g on a built motor can push over 400hp to all four tires. Marcus's car was notoriously lean. 550's are only a 22% gain from 450's. There's a 23% max gain in possible horsepower going to an EVO III from Marcus's setup. The fuel pressure regulator would make it just passable to run 550's on a truly maximized Evo III 16g from the numbers I've seen.

If you're not looking to absolutely max out the Frank 3, you'll be fine with 720's and a fuel pressure regulator. You should also be fine to max out the 20g on the 720's. The fuel pressure makes a much greater change the larger your injectors get.

I have no solid opinion on how much a stock 6-bolt bottom end can take. A stab in the dark says about 500whp on a perfect tune.