Any car lot selling, it is supposed to be federal emissions standards, and if cali truck should still meet those specs even if in different state. $10,000 fine per issue regardless of where you live/ bought it.
That said, it is illegal to speed and I got home a tad quicker today than the phone app says I can. So if you have it there is the issue. imo have the correct parts at least inthe garage incase.
Good luck with finding p.o. if you do, a couple pizzas goes a long ways for most people. But most of the time if someone bothered to upgrade a truck, they are usually gear heads and are happy to share stories of parts details along with how high they jumped it the last 4th of July party!