bjuice

Do you ever intend to you NOS in the future ?..also let me ask...are you shifting at 6,000rpm ?

the rule of thumb is to shift about 200 rpm above the max hp..so that when it goes into high gear it will not drop below the max HP rpm .

..most moderate 23 degree 400's i have had experience with over the years make the max hp in between 6500-7000..but i'm not saying your's does or doesn't..so do not read more into this than what it is...LOL........i am also not saying all 400's fall into this range...just the majority of the ones i have come across in the past including the last 3 i have owned...i have also noticed its more of a TQ motor rather than a high rpm HP motor compared to the 355ci...

My last 406 made 615hp at 6800..pretty decent steel head motor. aluminum rod's, 670 solid roller..

My wifes 406 is very very mild, dart iron eagle steel heads 520 flat tappet cam and it made 480hp at 6400......
ohh yeah..she has 26x10's et streets with a 4.56 gear..turns 6500 thru the lights in high gear (Turbo 350)..its just right for all motor...if we ever placed any spray on this motor we would have to drop gear to at least a 4.30 (Minimum) depending on how big of pills we use.. most likely 150 shot...also keep in mind a turbo 350 will create more wheel speed than a glide.......

So with all this said i believe a 456 gear will help you out if your 400 is anything other than mule...but i think you would have painted yourself in a corner if you go with a 456 if SPRAY is ever in your future....the extra gear will also be for nothing if you SHORT SHIFT it..


Brian