Stock is 195* and why, usually the timing is increased in certian areas. Like at WOT. With more timing, the car is more prone to detionation and preignition..
Detonation is the spontaneous combustion of the end-gas (remaining fuel/air mixture) in the chamber. It always occurs after normal combustion is initiated by the spark plug. The initial combustion at the spark plug is followed by a normal combustion burn. For some reason, likely heat and pressure, the end gas in the chamber spontaneously combusts. The key point here is that detonation occurs after you have initiated the normal combustion with the spark plug.
Pre-ignition is defined as the ignition of the mixture prior to the spark plug firing. Anytime something causes the mixture in the chamber to ignite prior to the spark plug event it is classified as pre-ignition. The two are completely different and abnormal phenomenon.
Reason for running a lower t-stat is to keep the heads, block, incoming air/fuel mix cooler to thwart off the effects of detionation/pre-ign. Which allows for more timing to be added. Why add more timing? Well it is used to fire the a/f mix at the right time to allow the pistion to be pushed back down into the cylender for optium power output. If you have the stuff mention above happening from hot spots on the head, block or wherever, it negates the added benefits of more timing.
Cliff notes..
Cooler t-stat allows the car to be more eifficent in making power!
AS for TBI cars, still haven't really messed with them. You have to do a few computer mods (like solidering new parts into the computer) that we haven't explored yet. When we get our hands on a few test computers (sometime soon we hope!) we'll start doing them.