So let's say you bought an exhaust system for your ST. You excitedly take your car to the muffler shop or jack it up in your garage to do the swap. When its all done you start up the car for the moment of truth and it emits a lovely sound or not. If you hate the sound, it is too loud, it drones too much on your commute, your significant other complains or you have to sell/return your lease, etc. you can have a Plan B: put back the stock exhaust. The stock exhaust is 55mm tubing but you have to cut it to remove it from the car without dismantling the rear suspension. Replacing the stock exhaust seems like a simple problem but finding a 55mm exhaust coupler at a reasonable price is non-trivial. At first I thought Torca had one, it was listed on their product chart but its vaporware, if they actually make it, they won't tell me where I can buy one. After that I eventually discovered that some VW and BMW use 55mm exhaust and OEM couplers are available but the cheapest I could find was more than $40. To that I say farfugnugen. Doing a Google image search, I found something similar to the OEM pieces for $11.75. That's a reasonable price for Plan B. The part number is 1K0253141M at autohausAZ. I hate paying as much for shipping as for the part so I bought seven to get free shipping. If you need a Plan B, let me know, I might be able to get one to you for cheaper than the retail price plus shipping. If you are local to the SF bay area, we might be able to meet and avoid shipping costs. I hope everyone gets an exhaust that sounds nice and never needs to be changed but I like being safe so I got Plan B.