OK, when you buy the standalone JWT conical filter, does it fit directly onto the mass air housing? What size is the flange inside diameter of the filter, 3, 3.5 or 4 inch?

 

Yes, It will fit the stock MAF pipe thingy. Bolts right on with 4 bolts

 

My real question is, i'm trying to use one of the new Amsoil conicals and wondering what will be needed to install an amsoil conical onto the stock mass air housing?

 

I believe you still need that velocity stack adapter. I know you do with the Stillen.

 

you could use a 3" maf adapter with a 3"amsoil cone. i reused my maf adapter from my maxima and threw a 3" k&n filter on it. i ended up ditching it back for the stock box with the lower resonator plugged and power duct removed but its easy enough. just get a 3" maf adapter, 3" cone filter(whichever length will fit, mine was 5" iirc) and 4 bolts/nuts.