My '06 Jetta has been hissing (much louder than the typical turbo whistle) for the past ~5k miles. The engine has 92,000 miles on it and within the past 3,000 miles has had both the EGR valve and Turbo replaced at a local dealership (which I don't plan to return to unless it seems these two parts were installed improperly or I have faulty parts). When we had the turbo replaced we were told that the "exhaust port had seized" and after inspection and confirmation from our third party warranty company it was replaced free of charge (to us). I'm not sure if the two were related but while it was up on the lift, having the turbo replaced, the dealership kindly replaced the EGR valve (which had a bad solenoid?) for an easy $600 (initially tried to get me for $1,500 ). I only mention these two recent repairs because I am pretty sure (after some extensive web searching) that this is either an EGR Cooler leak or a leak in one of the hoses connected to the turbo. I'm just wondering if anyone has any advice on where to begin the search (haven't had the wife help me by throttling so that I can be in the engine compartment or under the car but the best I can tell its coming from underneath the car). Also, should either of these things have been repaired/replaced or even noticed in the replacement of the EGR valve and the turbo? Lastly if this is another EGR issue is it possible to remove this system and still pass my emissions tests (Colorado resident)?! Just seems like a poorly engineered system that has been setup for a lifetime of expensive maintenance... Thanks for the help!