i just did a s13 sr20det red top swap.. everything works fine. i've got the car on stock boost right now. the problem i have is that there is a hissing sound coming from the turbo, kind of like a zzzzzzzzz sound... it does this when it when turbo starts spooling, is that shaft play.....are you not suppose to hear anything from the turbo? blow off valve is opening all the way. I checked for air leaks and found none. in between when i shift gears and step on the gas it makes a noise..if it is shaft play i'll end up having to get a new turbo.