canopy

there should be a little window up the front of the canopy it needs to be open a couple of inches . it acts a vaccum affect to keep dust out try it i hope it works.

What do ARB say about it?

Have you contacted them.. thats where I would start

Chas,
I have a dual cab hilux with and arb canopy, and I too had a dust problem. I also have a top front vent for pressurissing the canopy but living out in Alice Springs the amount of dust that gets is when that is open is massive. I did some investigating and found out most of the dust comes from the gaps where the rear tailgate closes against the tray, not the canopy after all.. I cut out a couple of bits of old carpet and glued them over the gap and this has stopped 99% of the dust, I don't think I will ever stop it all..
Good Luck
Yo Sam

gDay Chas ihave to agree with yo sam i owned a hilux with canopy for 7 years spent a hell of lot of time trying to keep the dust out ,ifound the tail gate to be the mian culprate i used a foam dust strip all round the tail gate it help but did not stop the dust totaly due to the fact that the trayon a ute tends to twist over ruff roads opening up gaps all over the place
Regrads
Bruce

i also have a navara dual cab with a dust problem , are all the bollts done up properly and there are a few holes in the tray that need plugging up and if you had holes where the bar went behind the seat you will need to tape or seal them up .
i just took mine off for the same reason to reseal with new foam (on canopy not ute) and there is a few places for dust to get in around the rear lower door and upper door sides but i sealed with an adhesive foam (hates the heat) .
likewise i tried the window open and this helps a bit.

anybody have a rear canopydoor outer (not glass) as mine is a little bent from a bad experience and arb want 320 for a new one ,mine has two handles and it looks like flexiglass challenge use the same fittings for these.
cheers