Gale Banks upgrade on Workhorse w22 with 8.1 GM

I have a W16 with 8.1 and Banks Headers, exhaust and air filter intake. It was on the MH when i bought it so i cant say what the differeance is. I can say this, i pull a 8.5 x 20 enclosed trailer with side by side and other stuff and here in the west have never lacked for power going over hills. Before i bought it from my friend we were in Idaho and he was able to keep up with my 2011 GMC dmax with similar load on the hills.