How much horse power extra hp can be added with turbo to your 99 Honda prelude SH?

It depends on what what turbo and components you use. With a standard T3/T04 turbo, no more than 8psi to be safe, your looking at about 70 horsepower gain.The reason you dont want to much psi on the H22A4 is because of its thin cylinder walls. Nick Sarith