OK the Spectre P4 did not work out, even though on paper it is only 1/2" longer than the P3 used by Apex, the stock air box had proven to be too unfriendly to a cone filter.
I did some research on the K&N round filters with offset flanges, even made some paper cutouts. I know one largest model that will fit, it is 7" OD, 4" height (filter media) with one offset 3" intake. But even this largest round filter will not increase the surface area by much, compared to the drop in filter.
Since the stock air box is designed for the flat drop in filter, I must give up and continue to use the aFe blue high flow drop in. Maybe someday when the price of the new aFe stage 2 drops down, I will get one.
BTW, I do have the Dinan Ram Air Intake style air duct drawing cold air from the brake duct, so I have no complaint about my intake at this point.
Last edited by adamsclubs; 12-31-2011 at 01:45 AM.