one thing you have to look at with the intake manifold is you need to look and see if there is any areas that might let the gas from the wet shot build up a puddle. it does happen. thats where most of your nitrous backfires in the intake manifold come from. if anyone is wondering what a nitrous backfire might look or sound like and the damage it can cause go to streetfire.net. they have a few videos of cars doing it on the street and on dyno runs.