Who makes this pipe?

[Antony250R]

This is from a 250R being sold on ebay, the owner described it as having a PSI pipe.
I have never seen one, can you still buy them? Are they any good?

[xlr810]

Yep. Sure looks like a PSI pipe to me. Looks like what they call the MX version. I had some experience with one, and I felt it had a pretty flat spot off idle, but pulled well in midrange and above.