1/2" will fit under my hood.
Micheal Yount had a good idea when I posed this question. Take some playdoh and make a ball or piece about 1" or 1 1/2" thick put some or these pieces on your stock intake where you think you might have clearance issues and close the hood. Open the hood and measure the thickness of the play doh where it has been flattened
Good thing I did that cause I was gonna buy a 1" spacer. Would have found out the hard way that it wouldn't fit.