http://www.roadraceengineering.com/eclgages.htm
"Why do I need an Exhaust Gas Temperature Gauge?
A leaner mixture will give you more power by making more heat. Too much heat, and things start to melt. You need to find out what's going on inside the motor before it's too late. Your car will never feel so fast as when the pistons are just beginning to melt. Most people who install an EGT are amazed at how close to the edge they are running. This is a must if you are going to experiment. We install the temperature probe in the exhaust manifold to get the most accurate reading. We prefer to mount the probe in the runner for cylinder number one since it seems to run the hottest. The probe can be installed without removing the manifold by drilling the hole with the engine idling. This blows out the chips. You will need a 1/8" NPT tap, if you dont have access to one, we have them for $12 "
"Why do I need an Exhaust Gas Temperature Gauge?
A leaner mixture will give you more power by making more heat. Too much heat, and things start to melt. You need to find out what's going on inside the motor before it's too late. Your car will never feel so fast as when the pistons are just beginning to melt. Most people who install an EGT are amazed at how close to the edge they are running. This is a must if you are going to experiment. We install the temperature probe in the exhaust manifold to get the most accurate reading. We prefer to mount the probe in the runner for cylinder number one since it seems to run the hottest. The probe can be installed without removing the manifold by drilling the hole with the engine idling. This blows out the chips. You will need a 1/8" NPT tap, if you dont have access to one, we have them for $12 "