Terril,
I think you got part of the recommended info. I think your buddies recommended you install boost pressure and exhaust temperature gauges.
The boost gauge is more of a diagnostic item. With tight intercooler hoses and good intake gaskets you'll learn what normal and maximum boost pressure is that your truck developes.
Boost is relative to horsepower... the more power you make,the more boost you make. If your engine developes an air leak you would be able to tell by reading your gauge. Boost leaks also cause a decrease in mileage.
The exhaust gas temperature (EGT) gauge tells you how hot you are getting the air/gasses that are devloped in the combustion chamber and going through the turbo of your engine,and it doesn't matter if you are stock or modified. You use it to keep yourself from burning a piston or turbo,and you also use it to determine when your turbo is cool enough to shut the engine off after driving the truck... wait til the temps get to 300 or below to shut off the engine. Also the EGT gauge is a great economy tool. If you keep your EGT's at or below 600deg while cruising on the highway,then you'll get your best mileage.
You see,these two simple gauges give alot of info,and like I said,it doesn't matter if you are stock or modified.
-Mike