Westtex what about the hole for the filter and intake tubes I was gonna get 2 inch long round aluminum tubes 4" or 4.5" diameter and have them welded on each side. I like the idea of not welding the whole box though. I'm thinking I could even weld some nuts to the piece the filter mounts to and put like sticky foam on the seams of the box and it would seal once the nuts were tightened down. That way that plate could stay in place to hold the filter and the rest of the box could be removed quickly.