Instead of accusing people of lying, I suggest you actually look into the matter or, well, ask someone. The sound engine is in fact backwards compatible, but it is different. All the previously documented API is fully functional, except some elements were ignored in the old engine. The new engine can't ignore them by design. By that I mean, now the actual position of sounds being played back matters. A lot. If a modder made a car that placed the engine inside the driver's head, previously they would've gotten away with it because the old engine simply didn't work correctly in that situation. It had no idea what a position was. Attenuation was basically linear, which is completely wrong. The new one does all of this correctly - so the content suddenly doesn't sound exactly the same anymore. Additionally, it also mixes every effect spatially, rather than just playing it on the front left and front right speakers as the old engine did, which was the whole reason we made a new one in the first place. There is no way to make this specific edge case work. It's a lack of information. The content has to be updated in that case. However, it's actually quite uncommon for it to break completely. So far, no example was found in the wild. More commonly the mixes were simply made for an incorrect attenuation curve, using completely arbitrary settings in the sound settings menu. Now that it is corrected, automatically adjusting the mixes is not possible because the information which settings they were mixed for is simply lacking. Hence the legacy sliders exist. Previously, those sliders didn't matter much. All sounds were mixed to clipping range (literally) and became one large compressed mess of loudness. This is no longer the case, so you hear subtle differences. This is by design, but shows issues with previous mixes more than the old engine did. Which is the whole point. If you wish to get the old sound back, feel free to just put a filter over the game's output that amplifies the sound to the point of clipping. You'll get a pretty similar experience then. Either way, use the legacy sliders until mods get updated. We've added those purely because we knew especially 3rd party cars would not follow general guidelines and thus sound more different from what they used to sound like than our own content, and we wanted to make sure players can adjust it a little. We've gone huge steps to make sure all existing content sounds as you would expect. That doesn't mean it sounds the same as before. If it did, why would we even develop a new engine in the first place? But it does mean that we did extensive work implementing features such as cockpit raytracing just to make sure all effects suit their cars well. If you don't like how it sounds, there will always be a build with the old sound engine on steam and no one's stopping you from just using that. Going forward, all new content will use the new system, documentation will be released etc. This new content obviously requires the new engine, but it's also mixed specifically for that, so there won't be any issues. That said lots of people enjoy the new sound engine. Everyone has different opinions, and no big release can please everyone. For example, legacy content's externals used to be much louder to the point where you could barely hear your own car when several other cars were around you. So we toned it down. Which means you only hear them when they're up close, which is more correct but ultimately limited by how the content had to be built. Still better than the old engine which straight up had no idea where to place these sounds so it just played them ontop of your own, coming from the front speakers specifically, not attenuated correctly. Also, for the record, we could've just gone and ignored any old content. Would've saved us like 6 months of work too. But seemingly many players enjoy using that with the new engine. So I'm happy we invested the time and money to make that happen. tl;dr: You can just use an old build for old mods. That's why they're still around. New mods, that require new builds, will be updated appropriately anyway. Old mods generally should work fine but may need small tweaks to ingame settings unless they were built completely wrong and relied on issues with the old engine in order to not sound "wrong". Oh, and by the way, the only reason I'm actually here is because I've received complaints about a user being toxic in this thread. I couldn't find anyone else accusing people of lying in here, so presumably those complaints referred to you. I hope all your questions have been aswered by this "lying developer", and now that there's nothing to complain about anymore, please calm down a little. It's not doing yourself or anyone else any favours, and won't change anything for the better either.