Tracks Rostock track almost finished but I need help.

[Gilles75]

ltcars has been very kindly helping me with this track and it's nearly finished but I have encountered a problem - when I make changes to the KN5 file and save it in 3Dsimed the KN5 file goes from 250 mb to over 2 gb and messes up all the tranparent textures so right now I cannot make any finishing touches to the track. I need to finish adding start cubes and pit cubes and replace a few buildings, otherwise the track is complete.
If you think you could help I can send you a private link to the track for you to take a look at, thanks.