I would recommend putting up a layer of body deadener like dynamat and then covering it with perforated vinyl. It will kill noise and improve cab temperatures. I salvaged the headliner from my donor truck. The PO paid $250 AU for it to be 'professionally' done and as I peeled it back expecting to see some kind of bitumised noise barrier I found - a $10 yoga mat... screwed over badly. You can get perforated vinyl on ebay for $15 - $25 per yard. I did look at custom headliners but they're only available for full size trucks like GMC, Ford etc. Would've been cool to get one with an overhead console and speaker mounts.