I put Kooks headers in my car w/custom down tubes from supercouperformance.com. I have a 92 SC with manual trans. The issue that I am having is that the passenger side of the exhaust sounds like it has a leak. When all the windows are closed I can hear it kind of sputtering (for lack of a better word). When I open the window, it seems OK. I checked all of the bolts and they are tight. The noise is more noticeable when going into gear and the car is between 1k and 2.5k under load. Any ideas??