Today I realized I'm missing a bolt for the header on each side of the manifold, so I was wondering if I would have to get these two bolts or does it really matter as long as it has the other seven snug into place on each header?

 

I would replace them. It would only cost a few dollars. I lost a bolt in one of my headers before. The header started to warp and gave me an exhaust leak.

 

I would replace them.

On an old 4 banger turbo volvo I had one of the bolts was stripped for the manifold and over time burnt out my manifold gasket and I would notice the engine bay considerably more hot after getting on it w/ the gasket like that. 350k on the car and she ran like a champ

 

Alrite thanks for the help..!