How do you increase the power in your 2001 Chevy 305 5.0l engine?

Start with a tune up, better spark plugs and a free flowing air filter like K&n will give you a little help, if it is not enough go to better exhaust and a performance chip from someplace like National Performance Center. Good advice. Also supercharging, turbocharging, and nitrous oxide injection can have a dramatic effect on performance. A set of free flow dual exhausts with headers will help by maybe 10h.p. Free flow filters such as K&N are of little benefit except at very high RPMs. There is no cheap way to increase power on this engine. It would be cheaper to sell this engine and purchase a crate 350, than to try and do internal modifications to increase power.