AFe at least has dyno results on a bone stock ST. FenFab has nothing to date so nobody actually knows what that one does.
Even then, would trust them with a grain of salt.
There was a big blowback years back on the Hellcat's with the AFe CAI. HP gain vs the stock was next to none, some actually lost power. AFe however, had it making over 30hp vs stock airbox. An owner did back to back runs stock vs AFe and posted the dyno sheets, runs were run same day.
Im sure it varies by car but would not go by their numbers either.