thats from either incorrect timing or valves being worn the fuck out, or valves mis adjusted, i would say timing though......if you have too retarded timing it ignites in the header, or in my case turbo manifold and would cause a turbo to prematurely wear out. if you could actually show me a spot in any honda manifold where some fluid will stay stagnant i will be amazed.. a clean NOS nozzle should be able to shoot nitrous 15 feet almost and the nitrous sprays thru the gas port which atomizes the fuck out of it, so its not like a gas hose or anything. remember it has 900psi behind it, that will pierce skin bro.