Once again using a PSI number for boost is hard to determine the power output, especially with the variety of turbo's out there. 20psi on a mitsu T-25 is significantly different than 20psi on a GT40, especially when is comes down to power #'s.
Here I have been doing some research to answer the same question you asked. I came to the conclusion that the k24a1/a4 on boost will safely make about 340whp usually with near matching torque #'s which is pretty impressive.
Some people would want more power from these stock engines (ex. 400whp). Some people that are very close to the 400whp marker have posted on this thread.
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