Making your own exhaust system is actually much easier than you would think. The main tool needed for the job, and one of the reasons not too many people opt to create their own exhaust, is a welder. You can weld up a catback with either a mig welder, tig welder, or an oxygen acetylene torch setup (arc welding is not too popular in exhaust shops). If you are going to be purchasing a welding rig for the project the best option would be a mig welding setup. A low amp model can be purchased from Harbor Freight for right around a hundred dollars. Harbor Freight also carries thick leather gloves designed for welding as well as welding helmets (to keep you from going blind).
(The welder above is the same model I used for creating my catback system/ also the best $100 dollars I've ever spent)
You are going to become well acquainted with one of the cutting tools below. It doesn't matter if you go pneumatic or electric either will work. If going pneumatic make sure your compressor is big enough to handle the air required by a pneumatic cut off wheel.
A chop saw would be the quickest way to do multiple cuts (pictured above)
An angle grinder with a cut off wheel is probably the cheapest way to go (pictured above)
Pneumatic cut off tool 6 bucks at harbor freight but you need a god tier compressor (pictured above)
Reciprocating saw (pictured above)
It is important when purchasing tubing that you understand the difference between press bending and mandrel bending. Long story short the "mandrel" bending technique produces tubing which flows more air (you want this). Ebay is a great place to purchase sections of mandrel bent tubing; there are even sellers who specialize in it. If you're lucky there might be a exhaust shop in your town that has a mandrel bender or sells sections of tube. In my case I had to use eBay since shops in my area were too expensive.
Mandrel Bend (left) v.s Press Bend (right)
For my catback I used a Magnaflow stainless steel muffler (at 2.5" in/out) as well as a Vibrant resonator (2.5" in/out). Both are pictured below.
Next head down to your local auto store and pickup a reducer to couple your new catback to the previous exhaust system. For my Mark IV 2.0L Jetta I used a 2.25" to 2.5" reducer which was able to utilize the stock clamp right after the catalytic converter.
For my 2.5 inch catback I had to purchase a 2.5 inch band clamp. This was to make the catback a 2 piece system that would separate right before the rear axle. This also allows you to take either the muffler or the whole exhaust system off later on down the road. If you feel inclined you can skip buying the clamp and have a permanent exhaust system. I'd recommend making it removable just in case emissions have a fit or something of that manner
Your last stop out shopping will be to the local hardware store to pickup a rod of raw steel. This is what you are going to bend and shape into your exhaust hangers. For my build I used a 3/8 inch steel rod which was right around five dollars at the Home Depot. It also ended up being enough rod to make four more sets of hangers for more catbacks.
Now with your:
- Muffler and Resonator (if needed)
- Reducer (if needed)
- Clamps (you will need one clamp for the rear section on a Jetta)
- Steel rod for hangers (3/8 inch)
- Mandrel bends
You're almost ready to get fabricating... Last step is to get some welding practice. In my case I used some extra tubing I had lying around and cut off relatively thin rings of tube. This will allow you to take a one foot piece of tubing and get ten to fifteen practice welds.
After lots of welding practice and 2 days later I ended up with this:
After lots of welding practice and 2 days later I ended up with this:
