That's exactly what I did on mine. 500# and airbags. Airbag man make two different ones depending on increase. One is 20-30mm and the other 40 to 50mm if I remember correctly.Closing the loop on this. The fox 2.5 is a notable improvement. I'm still a bit too heavy for my rear springs so I'm going to add the eibach 500lbs HD springs to the rear (+1.4") and to correct the front rake I'll install the eibach 1.7" front springs.
This should be great for my standard daily driver load and work well for when loaded up for camping. Just in case I'm towing something heavy I'm going to add airbagman bags to the rear. It's cost effective to do while I'm replacing the springs anyway and seems like cheap insurance.
I've sent a note to airbag man in Australia to find the right part number for the bags when using the HD springs (unless someone here knows)?
Afer driving this for a while I'll make a call if swaybar is needed or not. I suspect I won't need it.
I've talked to another member who have this setup for similar reasons and I've talked extensively with someone who works on Grenadier suspension all the time including doing race support and this has become the consensus amongst all the folks I've talked to
And yes, I acknowledge that I'm basically becoming a habitual modder and tinkerer on my Grenadier!