The A3 Exhaust Installation

Click on images to see a larger version

The heat shield that goes over the exhaust needed a deeper cutout to clear the longer stack of pulleys that came with the A3 engine. I think I cut about 1 inch extra out of the top of the big pulley hole in the center.

The A3 header pipe was not going to fit. Here I'm cutting off one of the vibration dampers to check fit. Before I was ready to start welding I cut the flange off flush. I then used the mill to cut out the old exhaust pipe from the flange to fit in the new pipe.

I went to Menlo Muffler in Menlo Park with a couple pieces of welding wire bent to the shape of the pipes I wanted. They sold me a silver streak glasspack muffler with a 2-1/4" ID to match the A3 cat outlet. They also bent up a couple of 2-1/4" 90 degree bends that I could use for the tailpipe and from the 2 into 1 on the header to the cat.

I welded the cat to the muffler first. Then I held them where they would give good ground clearance and look right. More clearance could be had at the cat at this point if the heat shield (top picture) was modified. I figured the clearance was good enough. I welded the cat and muffler assembly to the stock rubber mounted muffler brackets with a few strips of 1" X 1/8" cold roll steel strap. I used the same strap to span between the end caps of the cat. Otherwise the muffler mount would hit in the middle of the fragile center section of the cat.

With the muffler and cat installed I was able to finish up the header. The rear down pipe misses the motor mount by about 1/4". The two pipes come out in front of the left motor mount and then go straight back and up into the 2 into 1.

The 2 into 1 section is from the original Jetta header, as are the cat and manifold flanges. The 2 into 1 also has the stock O2 sensor in it. This engine has two O2 sensors. The second O2 sensor is on the output end of the cat.

Here's another view of the finished header. Next time I would use stock mandrel bends to maintain better flow.

After a few thousand miles I've had some trouble with cracks in the exhaust system. The Cat to Muffler connection needed reinforcing and now there are a variety of small cracks in the header. I would like to find a reliable flexible joint to put in near the O2 sensor to allow things to move a bit. I rewelded the system a few times only to have it break again.

This is what it looked like after one of my desert trips. It was so bad that I decided it was time for a rebuild. I scrounged a Flex joint from a racing exhaust and spliced it in with new 1-3/4" mandrel bends, when I was done it looked like this:

The new Ball and Socket Joint made all the difference in the world. I would not build a I4 conversion without one. The system has over 12000 miles with no trouble so far. Hopefully it will continue to be trouble free.
The muffler is still the silver streak glasspack muffler which is a typical piece of american made crap that makes "made in USA" such a strong warning label. It lost it's glasspack pretty quickly. I repacked it but it still sets off car alarms as I drive by. Funny I seem to remember that it was much quieter when I first made the system. I've now put in a short truck muffler, it fit fine. I hope it will hold up to the vibration.

Last update 8/6/99
Onward to the Cooling system ->