Now for the moment of truth, we turned the ignition key and immediately turned it off. The 5.3L was running terribly and sounded like it had a huge vacuum leak. After further inspection, the billet spacers that mount to the cylinder heads (shown in captions 10 and 11) were not properly lined up and actually caused a small flame to shoot out of the gap. We were forced to tear everything down and make a trip to the dealer to purchase new LS1 intake gaskets (as the small flame warped the original gaskets shown here). We were much more careful when repositioning the spacers and supercharger assembly and the 5.3L roared to life and idled like it should.