i have a 1989 535i and i recently installed the performance head from metric mechanic i do alot of street racing i i run against some fast cars and win by a few car lenghts but yesterday i took my car to new england dragway and i coulndn't get no better time then a 16.2 but the guys that i street race with where getting time of 14.8 i want to know y i wasen't no where near there time if my car is faster then thiers