both 8 and 9's are magnesium valve cover, I'm not sure if I would polish it, the heat plus oil will make it look terrible imo. If you are looking for the bling look, I would have it sent to jet hot for their sterling silver coat

 

both have magnesium covers

 

So I gave the polishing thing a try.. Stipped it, sanded it, wet sanded it and polished a large section on the top... It looked freaking awesome!!! Kind of a black chrome look in a way... I was all stoked on it, went to the fridge to grab a beer in celebration and in the two minutes that it took me to get back in the garage the damn thing hazed over. No matter what I did it would haze over and look all cloudy. Tried polishing and then clear coating it directly after and it still turned cloudy real fast. I was a bit pissed so I scrapped that idea and just shot it with some black. This is just the first coat so it looks pretty bad.

 

Why not just paint it?