change your own spark plugs, b/c it requires you to take the sparkplugs out to do a comp. test. do a compression test or go to autozone and let them do one, b/c the platnum plug w/ nitrous thing worries me. also if you wanna learn about spark plugs go to howstuffworks.com or do a search on google for spark plug info or somthin like that. who installed your nitrous by the way, and how big of a shot are you running?