I've been running with an open downpipe for the last few weeks, and today I just got my 3" straight pipe exhaust in from Josh Boam (mister3). I bolted it up and everything was looking good. But, afterwards, I noticed my idle goes up and down occasionally (anywhere from 800-1100, without touching anything, just goes up and down every few seconds). I thought it could be a vacuum leak, but it's nothing major. Does it have anything to do with the sudden restriction of more exhaust flow? or what? Is it just a coincidence? If so, what else could it be?