O.K so the exhaust of the 2001 ST sounds GOOD (it kind of rumbles), however the problem is a serious leak/failure somewhere behind the cat. Has anyone done a Borla or Magna Flo or Flowmaster or Dyno Max or other install from the cat back. Not looking for any increase in HP (but would accept any). Let me know what worked for you. I have a driveway (no overhead lift) lots of time, lots of tools and great vocabulary (Truck driver requirement). Looking for your input. Thanks.