First of all, we're gonna use the Mupen64 Plus Next core. You can install it by clicking on Manage Cores, then go to Load Core and start it.



Then you need to scan the directory where your -totally legal- digital copy is located.



By the way, if you want your UI to look like in these pictures (Inspired by the PlayStation menu), go to the Settings screen, search for the Drivers option and change Menu to "xmb", then restart.

Now load your game and open the Retroarch menu (By default by pressing F1).

Now enter in Quick Menu > Core Options.



Then go to "Framerate" and change "Original" to "Fullspeed".



And now restart.

With your game loaded, open the Retroarch menu, go to the Quick Menu and select Core Options just as you did before.



Here you need to change two things:

• Set the RDP Plugin to "ParaLLEI-RDP".
  
• Set the RSP Plugin to "ParaLLEI".

If your system can't handle this, you can go back to the "GLideN64" RDP Plugin and the "HLE" RSP Plugin.

Now, with both ParaLLEI plugins selected, go to the "ParaLLEI-RDP" settings.



And change the "Upscaling factor" to 4x.



And now restart.