I wouldn't give most people a kick for their opinion. How many people actually owned a 6.2, added a turbo, and used it for 10 years?
Most people don't know what a turbocharger is. You don't know until you have a 155hp idi 6.2 and try to tow an 8,000# trailer into rush-hour traffic. Before and after--then you know.
If you had a 155hp--which is the highest tuning a naturally aspirated 6.2 ever had from the factory--that means another 155hp worth of heat was blown out through the cooling system and another 155hp went out through the factory dual exhausts. A turbocharger is 2 parts--the turbine (like a jet engine) takes all of that 155hp going out through the exhaust and turns it into rotational force. It's about 70% efficient so 100hp is turning the compressor of the turbo. Can you imagine a 100hp air compressor? Mine at home is 7hp.
The 379 cubic inch 6.2 is being fed most of another atmosphere as it reaches 12psi at full boost with 14.7 at sea level being atmospheric. Banks tuned this motor with their kit at 209hp rear-wheel, no smoke--it was a dealer-installed factory option. That's 240hp, flywheel and 27:1 air/fuel, which shows no smoke. You start to get a little smoke around 22:1, which is what my truck sees. That's around 290hp. I don't claim that figure, but it's very realistic for the way it behaves and what the gauges show. I've takes 3 long tows (to New York City, Delaware and Wellsville, Ohio--all hauling cars) in an '03 7.3 Powerstroke, own a 2000 7.3 Powerstroke and have had a 6.2 with a Banks turbo for 10 years. I know what is what with these. This Banks 6.2 is stronger than the 275hp, 520ft# 7.3 in real use. Granted, the 6.2 is only 24 years old, and once it's out of warranty it will most likely explode and prove me wrong.