High performance endoresement is a one-time instructor sign off required to act as PIC of N-reg aircraft with an engine of more than 200BHP.
Some ground school and usually only one flight required.
Gorundschool (can) consist of some theory on turbo charging, super charging, operation of cowlflaps, fuel injection, engine temp management etc.
Any aircraft > 200 BHP will suffice for the flying part.