Pretty sure they don't have any or its just not public knowledge. From memory I couldn't find any either so think I just tightened them to what felt quite tight with a quarter inch ratchet which has seemed to be enough to keep it air tight without breaking any bolts or them coming undone over time. I'm pretty sure it's impossible to find room for clearance for one of the bolts for a torque wrench anyway unless the engine was out or you used loads of wobble joints which changes the torque spec anyway so would render it pointless.
I would use a quarter inch ratchet like I did or a long screw driver to get them pretty tight and then paint mark them so you can check if the bolts have moved or not over time if you're concerned. You can also check for air leaks with some wd40 if you're not sure if it's air tight or not.
