Does Gearhead get 6 might from Brutalizer on same turn or only 4?

Gearhead gets 7 Might (not 6 or 4) when Brutalizer is attached on the same turn.

Here's the breakdown:

• Gearhead has base Might 3, and its ability says: "Each Equipment attached to me gives double its base Might bonus."
• Brutalizer has a printed Might bonus of +1 in the corner (its "base Might bonus" per Rule 137), plus a conditional effect granting +2 if attached this turn.

Gearhead doubles only the base Might bonus (+1 → +2), not the conditional +2. Since Brutalizer was attached this turn, the conditional +2 also applies. So:

• Base Might: 3
• Doubled base bonus: +2 (from Gearhead's ability on Brutalizer's +1)
• Conditional bonus: +2 (Brutalizer's "attached this turn" effect)
• Total: 7 Might

The FAQ #8493 on Gearhead confirms this pattern — Gearhead's doubling applies to the printed Might bonus in the corner, not to extra conditional effects from the gear's text. And FAQ #9034 confirms Brutalizer provides both its base +1 and its conditional +2 simultaneously when attached.