I have a 06 sti.I got pulled over for loud exhaust so I welded the stock muffler back on but couldn't reach the top very well (small leak) car ran normal. 2mo. later I changed plugs (went to E3s) car still running fine. wife noticed car sounds louder,this is 3 mo. after plug change.now I can feel miss at idle and getting cell,no miss over idle rpm. any ideas? thanks
A leak that far back won't have any effect. Pull codes and check compression. Could have a faulty plug (hope), or bad ring land.
codes are po301 & 302 I've been checking on line and it looks like good luck to me, could be 1 of 15 different things. thanks for the help