Anyone who uses the dyno with dyno headers, ignition, carb and all that is wasting their time and money. If you are running a mechanical fuel pump you should be using that too, along with the alternator and water pump too.
With the heads available (the W2 has been around for decades and those heads will EASILY make 500 HP on a 318 or anything else) like the TF stuff that 500 HP is like oatmeal. It’s easy to do.