i know there are many types of timing guns and the ones that i am looking to get are those that have the digital RPM meter display. however, i couldn't find any one that i like from pepboys. so are there any suggestions?

also, when you flash the timing belt and see the lines... how do you know how many degrees it is being advanced or retarded? perhaps if someone can show me a site on how a timing gun works.. that would be great.

if i were to adjust my own timing belt... what tools would i need? and any "how to" sites on that as well? thanks.