By the way, there is a difference between the first "PF" J. Cepek released and the E-7/3 and E-7/4 ( SPS and early Mig-21PFM) he made available later. Sadly these models did not stay online for long, I remember downloading them on his website (
http://dcn44dt-okb-eee.webnode.cz/news/mig-21-pf-izdelie-76/) 2 years ago and I noticed recently they were not available anymore (and never uploaded on avsim.ru).
I wrote Joseph Cepek about this project to enquire about his other projects (Mig-21 U/UM dual seater) but he has not answered so far.
Here are the differences :
The initial PF has a pilot with stratospheric helmet/flightsuit for high altitude flights
The Je-3 and Je-4 have a standard pilot, wearing ZSH-3 helmet (wich is highly authentical)
Original Mig-21PF
E-7/3 & E-7/4
L'iguane