just a quick question to you dattosans are you refering to the extractors with 4-2-1 becuase turbos dont use extractors they use turbo manifolds.....if not o well
to answer the question yes you can run a stock engine with anywhere up to 30psi (member on this site ran a a12 with meth no probs) i currently have been running 15 psi on a stock bottom end for almost 9 months and have had no engine probs yet....