A couple of my own archive reposts and... (archive)

If you need to have your car smog checked have the muffler shop make a resonator and a cat converter with matching flanges that will allow you to swap them out. That way you can run a lower restriction resonator during the year. When smog certificate times comes around swap it for the cat.

One thing to remember: by reducing the backpressure you will cause your engine to run lean, and most likely result in poorer performance. You will need to have a custom chip burned for you to compensate for this reduction in backpressure. Jim Conforti will do this for you. A chip and a reduced backpressure exhaust system will breathe new life into your engine! It will, undoubtedly, be the best performance money spent.

Below are reposts of some of my personal archives.

"Fayhey reccomends using a single 3" pipe off of the headers. He then runs as long a
glasspack as he can (the type w/ the holes
inside, not the bent louvers). Near the rear of the car, he tapers the 3" pipe to 2.5 inches,
and uses a FLOWMAX 2.5 inch in
2.5 inch out muffler ($110).
If your car has cats, just order the OEM cat back from BMW. (Maxamillian.) The
glasspack takes place of the cats, and is
used as a front resonator."

"Believe it or not, I just had a system fabricated by Midas using a new line of Magna
Flow stainless free flow mufflers. It took a bit
of experimenting before I was satisfied. I tried a magna flow without a resonator and it
was too loud. We ended up replacing the
resonator with a free flow unit. Also had to swap tip several times. It is amazing what a
difference the tip makes in the sound.
You will have to find a shop that is willing to work on it but it can be done. Total cost
$550; including cat coverter, resonator and
rear muffler."

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