i currently have the setup for both of these and im wondering pros and cons of one vs the other ? 89 350

 

TPI:
Pros:
Good driveability
Good fuel economy
Decreased emissions
Cons:
Pulse-tuned ports limit RPM range
Limited air flow capability
Cost of improvements to above are expensive

Carb:
Pros:
Good air flow capability
Wide range of support parts available at relatively low cost (although a little limited for direct bolt-on for '89 model heads)
Cons:
Open loop system
Decreased fuel economy
Increased emissions (and technically not legal for use on public roads anywhere in the 50 states)
Need to provide for TCC lock-up if automatic

 

right now i get 12city 15 highway cus the computer is screwed up...at idle in park it revs from 500-1500..only in park
..and what is tcc lock up?...it is an auto 700r4

 

Torque Converter Clutch - it is locked by the computer when certain conditions are met such as 41 mph vehicle speed, 4th gear (in some models), high engine vacuum, etc.

If it doesn't work, you'll burn out the 3-4 clutch pack in the transmission. There are various ways to get that to operate, there is a tech article on the topic linked from the thirdgen.org homepage, and it's brought up from time-to-time on this and the Transmission forums.