I got an intake manifold for $25 too. Here in MA, I think junkyards are really unpopular they sell you anything just to make a dollar. Sometimes they don't even charge for little things if you buy something big with it. There's only like 20 I think in the whole state. I think people here kind of look down on them and they don't get alot of business. The EPA in Mass is cracking down on them because I think MA is so eco-oriented and yards are looked at as really damaging to the environment.

Injector size on an EFI controlled vehicle does not matter since the computer makes fuel measurements based on sensor feedback. Since TB mods don't affect displacement, you use the same amount of gas. If I put in 4.3 injectors the comp would compensate and run them really stingy to get A/F ratio in spec. the comp doesn't know how big the injectors are on an efi system. The sensors provide feedback based on MAP, TPS and O2 readings.

Now with MPFI vehicles the comp controls fuel delivery based on pulse width (time) and not on orifice size. So on MPFI vehicle, a bigger injector will spray more gas, since the injector is open the same amount of time but puts more gas in the cylinder. BUT, no matter which system, the comp is still going to seek a medium based on feedback. Bottom line is injector size is not a modification, since fuel delivery is ultimately controlled by the comp. The only way to get more gas in an efi engine is to rewrite the ecm tables or alter the sensors to produce different outputs.

Now swapping to a 3.4 engine or modding an engine by replacement pistons with different cc volume etc. it is encouraged to jump up in injector size to handle the fuel delivery load the ecm will ask for.

Choosing the right injector size is based on which one can handle the range of gas the ECM will request so as not to cause a limiting factor. Too small and they can't deliver gas quickly or efficiently enough, and too big the computer will struggle at idle or low speed since they won't be accurate enough.

This TBI mod increases engine efficiency by reducing the amount of load on the engine during the intake stroke. It increases Wide open throttle performance, and allows for quicker throttle response.

Think of engine power mods as two types, type 1 creates more power, and the type 2 prevents the engine from wasting as much power so it can put it to the wheels. The net result of both is an increase in HP, but they are different.

TB and exhaust mods fall into type 2, as well as intake mods, high flow cats and air filters.

Type 1 would be like increasing combustion ratio, changing cc volume, forced induction, ignition mods etc.

Kind of a shaky analogy but sometimes it helps to oversimplify things.