It would be nice, but could take a lot of time to create completely remake cars with a unique race modified style.
If PD would do this, here's the simplest way to create Race Modified cars for every car:
For Premium Race Modifieds, reduce weight by 5% over the full weight reduction, give it any body kit plus any racing wing from GT Auto (if that car has those body kit options), have both adjustable front and rear downforce settings that are higher than a street car aero wing upgrade (similar levels to equivalent touring, rally, or race cars), and the Base Model livery style. Optionally if it's possible on their schedule, also make a gutted interior (would still look like the street car inside, but with no passenger or rear seats.).
For the Standard Race Modifieds, give a 5% reduced weight reduction over a full weight reduction, add the slightly lower detail Base Model Livery, a GT Auto racing wing (if parts are available for the car) and adjustable downforce settings for front and rear (similar to Premiums).
Price would be between 75,000-150,000cr (depending on car). Like virtually all race cars in GT6, Nitrous would be unavailable for them once converted.
