I have been reading about exhaust modifications strictly in the interest of a more enjoyable sound. There is really nothing that can be done cheaply to gain performance as the MBZ stock exhaust systems are actually really well done. In fact, if you are not careful about what you install, you can rob your engine of power.

The most popular and seemingly less expensive option is to remove the center resonator and replace it with a straight pipe and then to replace the stock muffler with a universal Flowmaster or Magnaflow product.

All you need to do is find out the inlet size of your existing muffler, take some basic measurements regarding space for the new muffler to fit well in the space provided under the car, then go online and select what you need.

Now, if I remember correctly, you want to avoid a muffler that has a straight through path. You need one what takes the exhaust gasses and flows them through the muffler in a zig zag pattern before exiting. I think this emulates the OE muffler so there is sufficient back pressure.

Once you have the muffler in hand, take it all to a reputable muffler shop or customization shop and have them install the new parts. You might want to take this opportunity to have new exhaust gaskets installed where they need to be.

__________________
2006 BMW M5 "Heidi" @ 109,000 miles
2005 MBZ C55 AMG "Lorelai" @ 165,000 miles
1991 MBZ 300E "Benzachino II" @ 165,000 miles
1990 MBZ 500SL "Shoshanna" @ 118,000 miles

(On the hunt for a good used M103 engine as of 6/10/23, PM me if you have one to sell!)