its just a replacement box I'd still run an Injen,AEM or volant. the volant is a closed box so if you have a good/chill guy at the inspection area should let you pass
I've got one on my 08 and like it. When I initially put it on, I had my tuner off of the truck (was in the process of getting an ecu code fixed by the dealer; P0456) and I noticed a nice initial gain in low and mid range power. But when I put the tune back on my truck, I didn't notice a performance jolt like I expected. I guess that’s more of a tuner issue. The intake uses a tube that pulls air from the fender, like factory, but the Stillen tube uses the entire oval space that is there; I'd guess about 75% larger opening. If I had it to do over, I'd buy it again.