When I purchased the car It had nothing past the stock midpipe for exhaust. I installed a catless midpipe and ebay catback and now the car revs up and down between 1k and 2k rpms on a cold start. After a couple of minutes it levels out (I assume when the o2 sensor heats up) and the car runs fine. The only code the car throws is an evap leak. Any ideas?

 

Check neutral safety switch

 

brilliant!

beers