Whats a cheap way to get more horsepower out of my ford 351?

i have a ford bronco with a 351 modified and it is built pretty well. it has a pretty good cam in it and its stroked bored 30 over it has a carter 4 barrel carb and headers but im looking for a cheap way to make it run faster and get some more horses out of it without spending a couple grand on a supercharger or something