How much boost?

Hey I was just wondering what would be a safe boost level for a Si. I have intake, exhaust/gutted cat, mugen chip, and will be installing 450 cc injectors and a S-AFC. What should be a safe boost setting?

say about 5-7psi.

Originally posted by doug294
Hey I was just wondering what would be a safe boost level for a Si. I have intake, exhaust/gutted cat, mugen chip, and will be installing 450 cc injectors and a S-AFC. What should be a safe boost setting?


Well i'd say 7-9 lbs. Only if you upgraded your fuel pump. I would get a fuel regulator and fuel pressure gauge also. Its all about the air/fuel ratio. Get it tuned.

You might wanna get rid of the mugen chip ecu. I'm pretty sure its not the right set up for your turbo.

If you got an SAFC and 440cc injectors, your fuel management is probably good for about 9-10psi without having to upgrade anything. Since it's a stock engine and probably high mileage, I'd go 5-7psi on the street, and maybe 1-2psi higher for the track.

Why would the Mugen chip not be good for the turbo? It allows more fuel to be shot and no rev limiter/speed cutoff

the mugen chip advances your timing all to hell.

Maybe thats why my stupid check engine light keeps coming on