If you want to get them media blasted then take them apart. It’s not so much the damage that may be done during the resurfacing, but more the stuff that gets left behind. You want to make sure everything is cleaned out from the grit.
Look into soda blasting (using bi-carb) - it’s far less aggressive on the alloy and leaves a very nice finish on the horns. Here’s what my old RS5 manifold came back as … almost like brand new.
Not cheap though … guy in Brissy charged me around 130/hr if I remember correctly.
No one in rocky does it I’ve asked about it and water blasting. May just paint them myself, sand them back with steal wool then decide what I want to do
Once that’s done I’m worried about the idiot powder coasters we have here destroying them. Or is it pretty simple?
Plan b is sand back and paint myself with out ripping them apart.