Type 4 is correct accrediting to Corsair.
Cablemods = bit confused on this one. Gone to their website & the compatiblity page. for your PSU = C Series type 4.
The Page with C Series Type 4 doesn't list any cables for AXi, only RM Black Label/RMi/RMx.
The Page with the C Series 3 lists cables for RM Yellow Label/YOUR PSU/ HXi
Conflicting Info, I wouldn't take the risk. I'd buy extension cables instead. Buying the wrong cables would result in short circuit and damage to both PSU & PC.
EDIT: Corsair do make a White type 4 Cable Starter kit, I'd buy that instead.