Ok, so the other day a friend and I were trying to put a skunk 2 intake manifold on my ls/vtec. We changed over all of the sensors, hoses, throttle body, and alike from my stock intake manifold to the new one. We then bolted it to my cylinder head with a new gasket, connected every thing and proceeded to start it up. It started, but shook violently and threw some smoke out of the exhaust. We immediately shut it off and put it back to stock. It still did the same thing, so my question to you is what could it be? I put in new injector o-rings, spark plugs, and did an engine flush and oil change.