Enhanced Turbines allow the Phantom to drop the same amount of payloads at up to 25% faster speeds, thus reducing its vulnerability window.
— Gear Store Description
It turns out that the issue with Enhanced Turbines was that the Phantom technically used the Reload stat and NOT the Rate of Fire stat, as I had originally thought. That's why we saw a reduction in it's damage with the component equipped, even though the math was correct. As a little apology, we've actually upped Enhanced Turbines' effectiveness passed its originally intended power level. In a future release we'll probably cut the Rate of Fire part, since it doesn't actually benefit the Phantom at all and may end up just confusing things.