Solved:
Credit: Aelanna
Code Select
<ResearchProjectDef>
<defName>GunTurretCooling</defName>
<label>gun turret cooling</label>
<description>Gun turrets fire four shots in a burst instead of three.</description>
<totalCost>400</totalCost>
<researchMods>
<li>
<specialAction>ResearchModsSpecial.GunTurretCooling</specialAction>
</li>
</researchMods>
</ResearchProjectDef>
Credit: Aelanna