Turkey....
You are confusing Tuned Port Injection with Throttle Body Injection. Tuned Port Injection came on 350 Corvettes, Camaros, and some Impala SS models. The TPI is the one with the plenum tubes exposed and the throttle body at the front.

On the other hand is TBI (throttle body injection). This injection is a interim step up from the carburetor. It kinda looks like a carb and the "injection" is done inside the throttle body itself.....not a port injection in any sense of the imagination.

Throttle body injection is inexpensive and somewhat crude relative to port injection....but it's still better than a carb for stuff like off road vehicles because there are no floats.

Go to Fuel Injection Specialties web page
http://www.fuelinjection.com/
for a good explanation of the variations of tuned port jnjection

mike in tucson