thanks, any help is appreciated. if it helps, here is a rundown of the info I have so far:

K&N part# air flow dimensions (in)

RU-3530 646cfm 5.375 x 4.375 x 7
RC-4630 616cfm 5.5 x 4.5 x 6.5
RU-3130 536cfm 4.625 x 3.5 x 7
E-0998 682cfm unknown

BTW formula used for RU-3130 from K&N:
(base + top)/2=A, A x length x 6 x 3.14 =cfm

now i'd assume the E-0998 is the choice, but is that just a drop in filter? or will it work open air w/MAF adaptor? Also is CFM the spec to look for, or is filter area more important?

99 Silver CSVT #1081/2760 97 Nissan Altima 83 Corolla SR5 RWD bondo/rust body 'ghetto cruiser' RIP 78 Winnebago Minnie (Dodge Chassis 23') 440cid 4bbl.