HPE Exhausts are new products for us, so I do not have all the details, but I hope these links work.
These are listed for 999S, 999R & 749R
That is a comparison of the HPE 57mm system (red) against the standard(??) Termi system on a 999S. I also have a dyno chart for this 57mm system (RED) against a 57mm Termi system on the same 999S, but I cannot get a hyperlink to it and the system will not upload it to this forum. It shows a 4.16 bhp increase over the Termi system.
It comes complete with numberplate holder.
Hopefully more information soon
Sandbar