ok stock s13 sr20det has 370cc injectors.

***Correct.

the stock garrett t-25 is NOT the same as a mitsu t25 obviously since stock dsms can run their t25s up to like 18 or 19psi stock.

***Correct. The Nissan T25 is a Garrett turbo whereas the Mitsubishi T25 is a Mitsubishi turbine housing and wheel and a 55 trim Garrett compressor wheel. The Mitsu T25 uses the standard Mitsu turbine housing which has a round turbine inlet instead of the Garretts rectangular inlet. The Nissan T25 will eventually take a crap aftr extended boosting over 12 psi. This is because of its weaker thrust bearings which cannot handle very much stress. The thrust bearing can be upgraded to a 360 degree Perfect Circle bearing which can support a lot more power.

now
14psi is the accepted maximum boost level you can run because is it:

a) 370cc injectors max out after 14psi?

***No.

b) t25 becomes inefficient at 15psi starts blowing hot air or

***The bearings die over 12 psi. The turbo becomes *very* inefficient over 14-15 psi. This is because the turbine housing is very small and creates a tremendous amount of backpressure in the exhaust manifold. Higher boost pressure will cause reversion which will result in substantial power loss. Another thing is that at higher boost pressures the T25s compressor wheel is spinning on order of 250000 to 300000 RPM which simply whips the air at sonic speeds and heats it up immensely.

c) is it a combination of both?

****The turbo will max out before the injectors and MAF. The stock MAF tops out around 5.1 volts.

Just this morning I had to go help a friend who boosts way too high on his T25. He is blowing white smoke out of the tailpipe now and had to be towed home.

My advice is to stay at 12 psi or lower for the longest turbo life. Also make sure to use a 3 downpipe exhaust and a test pipe.

Peace