Way too small of a pulley. The only way you could reasonably run that size pulley is at least with headers/cam, even then you'd be pushing it big time. Anything under 3.2" should have headers and an intercooler, if not a cam too.
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'13 Mustang 3.7V6 - MT82
'00 GP SE (L67 Swap, XP, Headers, 3.25")
'98 GTP, '01 Bonne