I would recommend you do some research yourself and dont listen to those guys. Find out what other people are making with their setups, find out how to make it, and go from there. Stock motors can take a lot of power (as much as needed on the street, really).

I never see a reason to swap out or rebuild a healthy motor on a street driven car. When it goes, it goes, take care of it. Until then, you can make plenty of power.