yeah series one is the 1j were all familier with the series 2 are the vvti single turbo 1j found in the the jzx100 and 110 chaser kinda look like a 2jz... oh i think the series 2 1j comes in a soara as well but this im not to sure of.... they are quite hard to come buy... simular specs though the S2 aparently makes more tourqe down low and a little more up top...