I have upgraded my '89 5.7L TBI to a new vortec long block crate engine. I had a chip customized also, everything else is stock. Of course had to install the GM vortec intake for the TBI. Would putting in the 160 degree thermostat help performance?

 

while running cooler can help performance slightly, and sometimes allow you to run a hair more timing, unless you chage the temp that the computer goes to closed loop, i would run a 180* , not a 160.

 

I used to run a 160 stat and get by with it. The car stayed in closed loop and it worked fine. After the radiator got replaced, I noticed I had SES lights, poor mpg, etc. The "new" radiator wasn't full of crude like my old radiator so the car ran cooler with a new radiator. I switched back to the stock 195 stat, the car still runs a little cold because the fan is straight wired, but it stays in closed loop. (90percet sure) cause the SES light stays off most of the time and mpg increased.

I'd try the 180 stat unless you have a straight wired fan that runs all the time.

 

180 is the best choice for all around performance, cooler can give a little more power but engine life is much shorter.