OK mod time... Been playing since 29th October 2013, seen a LOT of different mods, however these are my personal favourites, in categories for ease of use,
First image I ever took, on that day ^
http://oi42.tinypic.com/s3gba1.jpg
For ANY mod site, get an adblocker and a fast finger to close opening pages upon hitting download.
I'll link to SCS Forum mods, but not third party sites just in case.
Sounds
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Sound Fixes Pack - A whole plethora of sound additions -
https://forum.scssoft.com/viewtopic.php?f=212&t=200919&hilit=sound+fixes
Dr Holz's Sound Pack - Re does all the sounds of the basic trucks, indicators, engine startup etc. If you can't find it I'll upload mine.
Enhanced Truck Sound Plugin - This makes the engine sound a lot better, similar to above and always introduces a "brake squeal sound".
https://forum.scssoft.com/viewtopic.php?f=34&t=165855 Just read this one CAREFULLY, to make sure it's installed correctly and sounds like the video.
Graphics
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NEXT_GEN Graphics Mod -
https://forum.scssoft.com/viewtopic.php?f=34&t=247693 Speaks for itself.
Physics
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AlexeyP's Physics Mod - One of the best in the business, AlexeyP does amazing work -
https://forum.scssoft.com/viewtopic.php?f=202&t=200807
Maps
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Promods - Free, huge and a ton of fun -
https://promods.net/index.php Keep this bookmarked for updates, it's not yet compatible with 1.30. Promods website also has a load order thread for using maps, so make sure you follow that, if and when you decide to add these or the game will not load.
Rusmap - Free, fairly big and very well made -
https://forum.scssoft.com/viewtopic.php?f=32&t=243183 A great addition to Promods.
The Southern Region -
https://forum.scssoft.com/viewtopic.php?f=32&t=212941 Mix of Southern Russia and whatever else is down below, has some nice dirt roads too!
Trucks
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RJL's Scania -
https://forum.scssoft.com/viewtopic.php?f=35&t=177963 This is the most extensive tuning modification for any truck I have seen, watch the videos to understand.
Ekualizer's Scania 143M -
https://forum.scssoft.com/viewtopic.php?f=35&t=187840 A lovely little older truck, has lots of character.
Ekualizer's Merc 1632 NG -
https://forum.scssoft.com/viewtopic.php?f=35&t=171463 Again another older truck, slow but enjoyable.
Aradeth's Volvo VNL670 -
https://forum.scssoft.com/viewtopic.php?f=35&t=206040 He stopped work for a while, so awaiting his return, similar to RJL levels of tuning.
Trailers
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Jazzycat's Trailers -
http://jazzycat.ucoz.net/index/mody/0-4 Among the best in the business, very high quality models and a pleasure everytime he updates them. In Russian and English thankfully!
All his work is on that site.
Misc
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HD And Colored Map - Better than the bland, grey one!
Real European Gas Stations - A nice touch of realism.
SiSL's Flat UI - a much cleaner, but "flatter" UI in the menu's.
Has been a while since I did a mod write up, keeping me busy!