The 4G63 engines found in 1990–1994 models have a 60 mm throttle body compared to the 1995–1999 MY's 52 mm. The intake ports on the head and runners of the intake manifold are also larger on the 1G. They also have larger crankshaft bearing journals to allow better lubrication. Because they look similar, it is important to note that the 1990-1994 cylinder head is more on the side of high air volume, while the 1995-1999 cylinder head is more on the side of high air velocity.