I would like to first off like to say that my objective is not to start a flame war but get I little more info before I get to deep. When I bought my 84 firebird the guy that sold it to me said that there was a original V6 in it( altho there was no engine in the car when I bought it), so the guy gave my a 305 ( minus the carb) from a 79 1/2 ton truck as part of the deal. Later after I looked up the vin it was a trans am with a 305 in it. I thought that after maybe I could swap in a tpi intake. So I found somebody that was pretty much giving one away ( intake, 85 & 86 computer, a wireing harness that has seen better days, disro, and a few other things) well I don't know if you can repair these harnesses or not so I looked at prices and frankly I don't spend that much on the car it's self. So my question to y'all is these A: am I really gonna get any better mileage with the tpi ( mainly highway driving) B: am I gonna have to replump the fuel lines on the car C: or should I cut my losses and just go back to carb And finally D: when will I get it through my 23 year old brain to ask before buying this stuff I didn't know really were to place this question. But I'm not afraid of doing some work but if I really need to buy another harness, fuel lines, pump, and what not it might not be worth an extra 2 miles to the gallon or the extra 6-700 bucks when I can get something like a new carb and intake

A properly tuned and adjusted computerized carb 305 with 2.73 gears, overdrive transmission with lock-up torque converter, can get 26-27 highway MPG. But, you have to keep your foot out of it.

TPI will do better overall, but highway MPG won't be significantly higher, maybe 28 MPG.

You would have to replumb the carb fuel lines, along with installing an electric fuel pump (TPI operates at higher pressure than carb). Many of the parts change (throttle cables, hoses, air intake, etc.).

My personal opinion is, unless you are making a significant upgrade such as LT1 or LS1, you're better off keeping what you have.