i started reading and when u didnt know wat knock was straight away i suspected u wouldnt have the correct fuel in it... i see it alot.... kinda makes me angry sumtimes lol..... if it was tuned on 98 and ur gonna go flog it sumwhere make sure it has that octane fuel in it. minimum u can run lower octane fuel if ur just lightly cruising but it still not recommended. my 2cents