He posted a comparison shot of stock with pnp kit vs s2k retro'd headlight (though the comparison wasn't 100% accurate as the s2k's headlight lense was off and the pnp kit probably wasn't the most optimal for output I.e. as close to 4300k as possible). With that said, the stock headlights are designed with halogen projectors, while most modern-day projectors are designed with hid projectors. The difference is better, more evenly spread light output; color rendering; and sharper "cutoff" (avoids pissing of oncoming drivers).
