They only look for codes right? Plug the scanner in, look for codes, no codes no problem. They are not checking to see if it makes the exact same HCs, NOX CO2... just checking if it all is working within the factory parameters. The cam is not big enough to cause misfires or else they could not run it in a 6.1 either. No misfire, not too lean then no codes. A reman 5.7 is $3700-$4200 ish, I can buy a low miles 6.1 right now for $3000, I know if I had the choice witch one I would run. Heck you can sell the intake for good money as you won't need it and get a good chunk of that back too boot. 6.1s start around $3500 on flea bay and carpart