Why is a bellows necessary?
Flexible exhaust bellows isolate vibration and absorb the expansion of your Exhaust system. Diesel engines develop an enormous amount of hot exhaust gas. The heat causes expansion and lengthening of exhaust piping. Every engine has a certain level of vibration and movement as well. The result of both rotating mass and the engines flexible mounting arrangement.
The sum of these forces can be destructive, a shoving contest between the engine and the exhaust piping. Traditional single ply bellows is only rated for 2,000 cycles. A high quality exhaust bellows will absorb the expansion and vibration, keeping your exhaust connections, welds, thermo blankets, and turbocharger housings in one piece for years to come.