I did 2 customers 300e's and I used a similar muffler to the AROSPEED. I put it on one customers car first without a center muffler and the low end growl was great but I knew the customers wife would complain. So I installed a Walker Turbo muffler. I installed the smallest one the had for 2.25" pipe.
and the results were great! It had the low end tone but was not loud. On the other customers car i installed a 2.25" Flowmaster muffler that was taken off of another car. (I used the Flowmaster as a center muffler) and then installed the Square Twin Tip "REMUS" exhaust from 3D Racing (bought off ebay from aimspot2000, btw: good fast service) and the results were great!
Sound is very unique and very throaty but quiet. I also did this same setup but with the DTM mufflers on my 190e 8v and a customers one.

Good luck!

NOTE: Them round resonators are worthless....the raspberries are still there. If you want to get rid of the rasp you will have to look in the junk pile of your friendly neighborhood performance muffler shop and look for a round type off of a Acura or Toyota.
Then the exhaust will be a little more quieter.