Why are 318's low HP and torque?

I slapped a slant six in my car without thinking it through and I'm really unhappy with it. I will take your advice and go back to plan A(stock 318 heads, intake, headers ect....). I'm all over the place because of that experience. I'm actually not fighting you guys, just myself and what I want to do with this car. Just afraid that I'll regret my build after it's all said and done.....again. And as you've all probably experienced... Once you are done with a project, you just want to go bigger after it's too late. Ill calm down and get the build done.