I used to put a cai on everything,until I clued in a stock engine is matched to the intake so velocity can be maximized throughout the entire rpm range,instead of just at wife open throttle.
My c3 has a k&n intake and filter and of course a throttle body spacer. I can say truly,without a doubt my 99(with a 5.3) has more part throttle power and this truck pulls great when floored its a bit sluggish when light inputs are required.
I'm not trashing you though. Modding is fun,and expensive.