I got an extra adapter which I ordered from the States off the ClubRSX forums. It is used to fit a Type S aftermarket exhaust onto a BASE model Acura RSX.
This is a rare item, as many of you guys here are asking about trying to fit a Type S exhaust onto a BASE RSX.
Price: $45.00 FIRM.
If it doesn't fit on to your RSX, then I would gladly refund your money, but I have researched the ClubRSX forums as they all state this is the size/shape that everyone uses.
I ran into problem using this adapter, I had to buy another 5Zigen one for a lot more money than this one, plus some custom welding. They suggested it might be my exhaust that I bought that was a bit funky as everything did bolted up and lined up correctly, but was slightly rubbing on the underpart of the car.
This is the price I had to pay after taxes, shipping, cost of the item from the States. So I am not trying to make money off anyone, but if you are lucky enough to use it, then by all means try it out. I am just trying to make up for some cost for the other adapter I had to buy. I am accepting payment first, but if you run into problems, then I will gladly refund your money.