Actually, it's really simple to convert a regular NR03 track into one suitable for OWR. All you need to do is add a PTA section to your Track.ini, copy the regular grip section, paste it under PTA and increase the grip to about 1.6 or so or whatever best suits the track. By adding the PTA part to the .ini, you can increase the grip for the open wheelers without effecting the CTS, GNS or CUP physics. Now you can run both the Indycar mod with the correct grip and still have all of your other mods uneffected as well.
I can't remember what exactly to add to the ini for seperate physics, but it this it was something simple like just [PTA] or [CUP].