I have a custom backbox for sale that came from my Mk3 N/A Supra. It came with the car when I bought it and it had been attatched to what seems to be the original exhaust from the car, which had literally rust itself into 2 halfs near the end. Binned the exhaust, and have replaced it with a whole new one, so I have no need for this backbox now. It's in excellent condition, as you can see from the pics.
I don't know who makes it, but it has the following stamped on the back:
XRC01
RSA-C01
C09R1-1M2

"XCR01" follows the naming convention for Magnex exhausts, so it may be from them.

Looking for £50, plus it'll probably be about another £25 to post, as it weighs a fair bit. (If it costs any more, I'll cover it)

Pics:
Side
End