it backfired b/c i didn't use my purge kit. basically a load of air went into the engine in front of the nitro, blew out a spark plug or 2 and all the nitro behind it shot thru the engine and out the back end. it blew the MAP senson (manifold absolute pressure). afterwards it was a bitch to start (i had to give it gas) and i couldn't go over 4ooo rpms. it was fine thou after i got the new sensor. and w/ the o2 sensor, the nitro will clean out all the crapy buildup inside your engine and spit it out the back. the o2 sensor on your exaust (headers) will start collecting this and it'll reach a point where it may not work anymore. if i can i want to get a hold of a remote bottle opener b/c you usually don't drive around w/ your bottle open so a lot of races i've gotten into i've been forced not to use my nitro b/c the bottle just wasn't accessable. sometimes i can reach back and open it, but thats really awkward and mosttimes i don't have time.