Why a boost guage 6.5 diesel

[1995Chevy3500]

A pyrometer I understand but why do I need a boost guage? I have stock 6.5 diesel in a 95 chevy flat bed tow truck, I dont plan on any engine or computer mods....Im looking to open up the exhaust,maybe get rid of the air filter box and put a open element filter, and thats it. Please tell me why under a stock engine would I need a boost guage, what will the boost guage tell me while towing or towing up a hill? Is there any other important guages I will need? I have a manual 5 speed transmission so no need for tranny temp guage. THanks for any imput, I did do some searching on both guages, just wanted to ask a for sure thing...thanks

[Shaners]

I can't see why you would need a boost gauge... The pyrometer or turbo temp would be all you would really need if you're hauling a heavy load.

[silverado3500]

A boost gauge really isn't essential on a stock truck.