AT Throttle Body Swap, and JDM intake goodie info..
the AUTOMATIC throttle body is 66.5-67 mm on the intake side of things and 60mm on the plenum gasket side. Make sure to get the same year throttle body when making the switch, because TPS suppliers may have changed between OBD and OBD2 years, not verified though. Also, the Apex'i S13 Power Intake part no. 507-N004 bolts directly onto the stock 80mm inlet MAF. no need for odd fitting MAF adaptors, plus if you're into JDM brand stuff.. points for you. hahaha. Its a pricey intake brand new, but the Apex'i Power Intake filters alone have shown more gains than K&N, Injen, HKS/GReddy mushrooms and the like. Lots of engineering r&d goes into these filters. retail is $100 for filter alone. intake kit is $180-220 shipped.