I think you have 3 options, or at least this is what I found buying mine:
1) Buy a "Sports Exhaust" from one of the many US suppliers. If you are otherwise modifying the car then the non-standard parts won't be a big deal. Also, lots of people want the rubbley zoom sounds.
2) Buy a factory-style exhaust from one of the suppliers in Europe. They are setup just like the original exhaust if you want a stock-fit. But I found the shipping was exorbitant - something like $500 to ship a $200 exhaust system.
3) Spend days trying to find a stock exhaust system one piece at a time, from one supplier at a time in the US. Many, if not most of the US suppliers buy from the European suppliers and hold stock in the US. As that stock sells down, they may or may not have what you need, and who knows when they will get more.
My car is 99% original and unmodified and I'm keeping it that way, so option 1 was out. Because of the cost and time involved in #2, I went with options 3. I don't think I bought more than 2 parts from any one supplier, and at least 50% of the suppliers who said they had parts X, in fact did not. It's a time consuming process with a lot of googling, but I finally got everything.
You didn't mention whether your car is an S or an E? Mine is an E and that makes matters worse because the exhaust is different from the S. Many of the E parts are common with the 164. If you have an S you might have an easier time of it.
The other thing I found is that the E tailpipe should include a resonator, but it doesn't appear anyone makes them. I tracked down 2 tail pipes with resonators with the correct part number and both arrived with no resonator - just a straight pipe. Neither of the suppliers could explain it, so I've thrown in the towel on that one. Again, this only applies to the E.
Good luck.
