Has anyone installed this header to the stock DP? Can I use the stock studs and bolts or do I need completely new, different bolts and if so what size and type is best?

 

You can probably reuse them...if they are REALLY hard to get off(depending on how long you had your car...) you might have to cut them off...you might just want to get new ones...look at your manual to get the right size...maybe from the factory...or ZZP....just to be on the safe side...up to you.