you can probably change the exhaust housing to something smaller and put it on a smaller engine. I wouldn't run it on anything under 2 liters. That being said, if you've got built internals, run it. As blackshine said above, they dont' really get efficient till after 30psi. Get some built internals and run about 35ish psi and you will have a very fun turbo.

Oh and this is a variable vane turbo, so you will have to figure out something to drive the vanes. I forget if this system uses gas or a solenoid to control them. Google is your friend in this case.

I'm tossing a holset onto my car. We'll see how that one does.