Many classic car collectors and enthusiasts prefer vehicles in their original, period-correct condition. Altering a classic car by installing modern features or making significant modifications can diminish its authenticity, historical significance, and thus, its value.
However, it's worth noting that preferences can vary among collectors and enthusiasts. Some individuals might appreciate the added safety and convenience that ABS brakes provide and may be willing to accept the compromise on authenticity. Ultimately, the impact on value is subjective and can vary depending on the specific car, the level of modifications, and the preferences of potential buyers.