I put a Borla Cat back system on my car 6 months after I bought it and never regretted it. It was mid '91 and Borla had their R&D shop about 15 miles from my house; After I had the system for a few weeks I felt it had a little too much drone at the RPM range I was usually operating at. At the time I commuted 60 miles to work and after an hour of driving each way it was a little irritating. I went over to Borla and they put a small venturi shaped baffle about 6" back from the end of the tip. They tack welded it so I could remove it if I wanted. I took the car to JWT a couple of times for a dyno tune and Jim would say how nice it sounded, but too bad it was not as efficient as their system. Later I started using SZ's services and every time I take my car in for a retune after a mod Greg would give me a ration about my horsepower robbing system. I prefer comfort with a measure of power, not the other way around.