I have two LFS folders, one normal one (currently Y30) and a folder for LFS tweak to play around now and then. Thats Patch Y. If i wanted to race online with the Patch Y folder that has tweak, is it ok to go online as long as i don't turn on LFS tweak or will it detect that tweak has been used and me getting banned?

Thanks.

I did run a server with a tweaked cars some time ago. I used some special layouts to slow the lap times down so the personal best times wouldn't be affected. Or WRs broken.

I don't know if any special measures are required, Huru-aito iirc did host some rally cross tweaked cars as well without layouts so I'd guess as long as your purpose is to have fun it's all ok.

If im racing against other people? IE, a one off round in MNR or a series in MNR (MNR - racing league)

Personally I see no problem but if you want to be really sure you ask from the people who make the calls. But tbh. I can't see any reason why it wasn't allowed to host races on tweaked server. Just remember to tell your racers that their LFSworld PBs go "worthless" if they drive tweaked version of a car online

Only a problem if you're making the car faster, of course.