Hypertech 160º Thermostat for the 3.4L V6
by Jordon Musser

Overview
The Hypertech 160 Thermostat is designed to let coolant flow through the engine at a lower temperature, so that the engine will stay cooler. I bought this from Internet Racers Supply for $14.95

Installation
Although generally installing a thermostat is an easy job, with the 3.4L V6 it become more difficult  because of its location, right under the throttle body.   The first step is to make sure you have the right tools. You will need a standard 13mm socket, a 13mm socket with a built in universal joint, a 6in extension, and a racket with a flexible head.  First loosen the right bolt on the thermostat housing(when viewed from drivers seat).  Then remove the throttle cable cover on the opposite side of the TB.  Now you can see the other bolt that holds the thermostat housing on.   This bolt is tricky.  First put the 13mm socket on the ratchet, and bend the joint in the ratchet to 45º, and wiggle the head of the wrench until you get the socket over the bolt. Be careful not to break the temperature sensor off that is located next to this bolt! Now loosen the bolt 1 full turn like this.   Now remove the ratchet, and see if you can loosen the bolt the rest of the way with your fingers, if you can't, use the socket with the universal join and the extension to get the final bolt out. Once both these bolts are removed, pull the thermostat housing off the block, a little coolant may drain out.  Now remove the old thermostat, and put Hypertech thermostat in being sure to use the o-ring that was on the old thermostat(replace if it is torn). Reinstall the parts in the order you removed them, being sure that you tighten the bolts down on the thermostat housing equally. 

On the Street
The engine stayed MUCH cooler on the highway(about 170º, as opposed to 185-190), however the engine was not much cooler when stopped in traffic

At the Track
The engine stayed cooler when staging, and also took less time to cool down in between runs.

Conclusion
This modification is almost mandatory here in Dallas TX. It does make an impressive difference