I've seen A LOT of posts about making HP with a 318-So why is it so ???

In a nutshell, not all of us care about maximum horsepower. I talked to a guy last night that bought a 69 Road Runner that had been raced. 440, dual quads, big cam, 11.5/1, 4 speed, 4.10 gear, etc. He is in his mid 60's and had fun driving the car but he doesn't enjoy driving it. He doesn't take it far from town and it sits in the garage a lot more than it should. We talked about de-tuning or doing a 383 and rear gear swap to get him back to a cruisable combination that he can enjoy. I am going to help him get there.

That'll be a fun project!