How much of an advantage does a racing modded car have over an unmodded car of the same? (so you got two of the exact same car, same tune-ups only one has a racing mod and the other not)
well to get racing mod you have to have performed weight reduction levels 1, 2 & 3, so if the non race modded car hasn't got weight reduction, I suppose the race modded one is lighter. Other than that, the only advantage I reckon is a cool looking body kit (sometimes )
buy the racing mod. to make your car perform better you can alter downforce. higher downforce, more grip less acceleration. lower downforce, less grip better acceleration.
better grip means a more responsive car. you can have the downforce on full and it wont make too much of a difference to the acceleration accept on the 400 and 1000m test course.