Replacing my stock exhaust with Gil aluminum manifolds. Grade 8 or stainless bolts?

Stainless. The torque spec is 25ft-lb, shouldn't need the extra strength and would lose corrosion resistance.

+1. Trying to remove exhausts i put on the hatteras 5 years ago. Bolt heads corroded down so it is a serious problemo.

and use antiseize

not a good idea using stainless with aluminum...disalike metals

How is that even a real concern? Your exhaust bolts should never be submerged, much less for prolonged time. Secondly, if it does bother you just add an anode (which won't do anything because your engine compartment shouldn't be flooded, but I digress). Sure, you could use an aluminum bolt but youve just moved he corrosion cell to another area.

Ideally wed use like materials always, but in reality that isn't always the case.

this always makes me laugh, so the stainless fittings threaded in for the water passages are ok but don't use stainless bolts to hold them on to the heads? Lol

Exactly! The galvanic corrosion stuff gets parroted because most don't understand it. You need ample electrolyte to make it work (what plants crave, lol). If your exhaust bolts are in that condition they're not even on your priority radar.

Like worrying about stainless seel valves, steel springs/retainers/cups, on aluminum heads....LOL.

However, if using stainless bolts in aluminum heads, please,,as noted above...use some antiseize. I prefer copper antiseeze because I just do.

i like the nuclear grade antiseize because,well because i get it for free.