255ph 2007 Volkswagen Rabbit or 1989 367hp 5.0L Ford Mustang?
First, he is crazy to add a turbo to a car that is still under warranty. It will be voided and if anything breaks he is screwed. Second, the motor in the rabbit is not the same as the turbo charged versions. THey have different cranks, bearings, lubrication systems and many other different parts. Just adding a turbo will shorten the life of all the drive train components and will most likely break a few of them
Third, there is no replacement for displacement. The potential in a 5.0 Mustang is almost limitless. The 5.0 is a tough motor and can take a real beating. The rabbit will handle better unless you get a 2004 or newer stang, but a Mustang with a built motor and some suspension work is a great ride. It will also hold some of its resale value, the Rabbit will be worthless.