Install using mod installer(only for 20.06.17): Put "NewRacingMuffler200617.exe" in root game and start install.
Manually install(for any version): instruction inside.
Why mod installer install mod not correct?
I'm doing mods only for main(not experemental) Steam version of game.
After any game update/quickfixes mod installer need make again.
Usually after game update in few days developer of game releases hotfixes. I'm update my mods after few days after last hotfixes.
So if mod installer install mod not correct - most likely game developer released update and mod installer not updated for new version.
Why mod installer detected as a virus?
My Summer Car officially not support mods, so you can't just download mod and put it in mods folder.
My Summer Car made using Unity3D game engine. Game resources in Unity3D packed in game archives(as in others modern games), which can't possible open by ordinary archivers. For edit Unity3D game archives there are Unity Assets Bundle Extractor, I and other mod makers use it for make mod installer. So why it detected as a virus? Mod installer make changes in game files(viruses make changes in Windows OS files) and it can be detected as a virus.
Yes, it does not sound very convincing, but:
1. You can use manually install;
2. This mod download many people and no one complaint, that my mod deleterious or steals accounts. I start make mods for My Summer Car from november 2016;
3. You can make own mod installer and scan it on viruses, you will get same result as my installer;
4. You can scan mods with mod installer by others mod makers, you will get same result as my installer;
5. You can use Sandboxie for control, what files will be changes(viruses make changes in Windows OS files, mod installer make changes in game files) or VM VirtualBox for use mod installer, then delete virtual Windows OS(for users with maximum degree paranoia).
My other mods: http://www.racedepartment.com/downloads/authors/roman266.249988/