I just recently put Gibson stainless steel headers (Gp301s) on my durango (5.2l). Now I hear a slight grinding noise in the front. I thought it was the exhaust so I took it in and had the exhaust checked out, everything was ok so I had a flowmaster installed. (sounds nice!) But I still hear that grinding noise...I'm thinking its transmission since it has a small leak. I put it on my friends lift and noticed the rear end is leaking by the yoke and the right/front right axel is leaking...(any idea on how much that will cost?!) The Durango has 120,000 miles, runs really smooth, just had the inake plenum gasket replaced. I have the hypertech programmer installed, headers, K&N Gen. II intake and flowmaster exhaust...is there anything else I can do to increase power/speed/gas mileage? (after the leaks are fixed)