As you know, Moot, some upgrades became factory and depot-level standards. Certain changes were "standard" ones. On the other hand, pilots just chucking gear off a plane in the hope of making it fly better, is what HTC does not cater to. VVS pilots hacking metal panels off of their IL2s and sticking a guy in the open hole with a tail gun is a field mod. Swapping out hurr1 guns for 2x20mm in VVS hurricanes is a field mod. Removing standardized parts from a plane because a small number of pilots want the cowl guns removed is a field mod.
However, the 190Gs had the cowl guns removed as a standard, but this was to counteract the weight of flying with 2 underwing drop tanks and a centerline bomb. It wasn't for dogfighting considerations.
In a 190A, pulling out the cowl guns saves you very little weight. You save more weight by leaving off the outer guns.