my cousin blew his block and has replaced it with a gsr block in his 99 civic si. He has also installed ctr pistons , gsr rods, ctr cams, aem cam gear. The car is basically stock with lowered springs and cai. After the rebuiltign the bottom end and keeping the stock b16a head, the si is running much stronger than before. We've raced stock si and pull approximately 4 car length from it at the end of 3rd gear, but when racing other cars ( gts celica & hb with b18c1 both with i/h/e) 3rd seems to pull much slower than 2nd gear. while running the hb, the si was ahead 1 1/2 car length at the end of 2nd but at the end of 3rd the hb was 1/2 car length ahead. similiar to the gts. I am wondering if it has something to do with the fuel, possibly the si needs fuel regulator, or is it something else. your advice will be greatly appreciated, tanx