I own a 1999 pulsar with a ga15 engine. I've been thinking about getting a ga16,sr18or sr20 motor for my car. The ga16 cost more than an sr20 where I come from. what the heck should I do. I have the head of an sr18 which is equivalent to an sr20 so I was gonna use the TB from it on the 15 but can the intake manifold and injectors fit too. Should I turbo my 15 instead of putt in the 20?