Ok for those of you who have not already done this, due to this announcement: http://discoverygc.com/forums/showthread.php?tid=129201 it is now illegal to edit ini files in freelancer even if its just for FX. Which means the 4.85 Mortar FX mod is no longer permissible and thus needs to be removed.
There are two ways this can be achieved, the most advisable way is to just re-install the discovery mod.
If you can't be bothered to reinstall your game then you can just replace the files copied from the Mortar FX mod with original files which will thus remove the mortar fx mod from your system, details and link are provided below.
Installation Instructions:
go into your file directory where 4.88.1 is installed this is usually in C:\Users\Username\Appdata\Local\Discovery Freelancer 4.88.1
1. Once in the game directory goto DATA \ EQUIPMENT \ and replace the weapon_equip.ini file with the weapon_equip.ini file in the zip file you have just downloaded from the link below.
2. Next goto DATA \ FX \ EXPLOSIONS then copy and paste all the files in zip folder - "Data - FX - Explosions" into DATA \ FX \ EXPLOSIONS
I have now removed the links to the uninstall mod for 4.85 Mortar FX, this is due to the fact that since its upload the server itself has updated and thus the uninstall files may not be compatible with the current discovery mod files. So the links were removed to avoid conflicts!
If you still have not removed the 4.85 Mortar FX mox then I suggest a complete reinstall of Discovery to ensure all your files are vanilla.