i was wondering on a cat back exhaust do i have to change the entire exhaust system or just the cat? cause if i cant im going to try and get away with buying the cat and bolting it on. im only looking for about a 20hp increase with a exhaust change.

 

The name itself should give it away. A cat back system (short for Catalytic converter, back) is mounted from the catalytic converter and back. The system should include every component located downstream of the catalytic converter. This includes pipes, tips, resonators, and mufflers. I have a 1998 3.8l and Flowmaster makes a great sounding catback system. It's the Flowmaster 80 Series 'American Thunder' system. It's currently installed on my car. I opted to replace my catalytic converter, as mine was severely damaged. The catalytic converter, unless you but an OEM style direct fit ($$$), is not a bolt on application. It requires an airtight weld, which could best be achieved by a skilled MIG welder. Stick welding is a tad overkill for this project. I bought the OEM style direct fit, which set me back $250.00. It took only 30 minutes or so to install (given I had a lift, assistant, and had let the entire system cool).

 

On a related note, how important is it for exhaust tips with a resonator to be welded all the way around, as opposed to spot welded? Assume that this is a clamp-type tip with 3 screws and that the tip connector is bigger than the pipe it connects to... I just had a tip like this installed on my '95 with the screws engaged with a couple spot welds and I am wondering if I might get a different sound if it was fully welded around, dunno if airtight matters...

TIA