i take it your auto because of the times u run....us auto guys would be better off gettin a 4-2-1 designed header because of the low to mid range power the 4-2-1 makes....we need all the help we can get off the line and this one should help....the 4-1 will help also but by the time we start using the power it makes where already behind....the faster your 60' time is the faster u will be....the manuel guys dont have to worry about the low end power too much when racing because they rev up to take off....taking them out of that range....we cant....so our problem is in the take off....the more low end power u can make..the faster u can get off the line and that equals faster times.....this is just my thought on it.....u will feel the 4-1 alittle but notice the 4-2-1 more because of where it makes the power.....

dfresh