can anyone give me a detailed guide on how to download the blow off valve mods for demo racer?

CAN ANYONE give me a detailed description on how to download these blow off valve mods? can u do it on demo??

well im all new to this so sorry about the mix up lol im looking at real looking cars etc and someone said i can add blow off valves ands stuff

As soon as i downloaded LFS i saw that there was loads of mods etc but the thing is i have NO IDEA how to download them and make them work!! i really need a detailed description on how to do it if at all possible, will be appreciated!

THANKS!