I run the 40hp on my Spartan. The truck runs cleaner (visually) than my 6.0 did with the EGR and cat in place. I would love to see how my truck would perform on a sniff test. I may try it just for kicks and giggles. Even my 200 file runs clean for what it is. As for a drone, it is non existent even with my 5" exhaust with no muffler.

 

Towing I'm stock Mod. Rolling Coal is when I mash the accelerator pedal to the floor.

 

I also run the 40 hp Spartan tune. Never have tried any of the other horsepower offerings on the tuner. I feel so sorry for the guys that run stock and experience failures, 80% (my estimate) attributable to emissions equipment. Deleted at 40000 miles and currently have 106000. So far you don't have to worry about emission testing in Texas for diesels. I used block off plates on my EGR just in case I have to reinstall the emissions stuff. Its a pretty painless operation. The tuners aren't cheap but worth it in the long run for the health of your engine.