They don't effect much yes, but they do some. I was just answering his question.

On the newer cummins in the big rigs,they do have the silencer ring in the turbo.
And i'm going to a dyno day next month and i'll test this.

97cummins, that would be greatly appreciated and will put an end to the theories on this :)

We've got a cummins qsx genset with 900 HP pushing 800 kW and as quiet as it is no silencer on the hx80 it runs

Sorry i meant the dyno day is the beginning of may,i'll still test this.
the cummins isx motor has the silencer ring in it.