Did you disconnect the negative battery terminal before performing the install? If your answer is no, go out and do it now! While the negative battery terminal is disconnected, get in and pump the brakes a couple times to ensure that any residual power is drained from the ECM. Now connect the negative terminal back up and make at least 3 or 4 driving cycles.
What we are doing here is clearing the ECM's adaptive memory. Your car's computer needs to re-learn the fuel trims now that its intake is much less restrictive. This WILL make an improvement in performance!!!
U.M.
P.S. This procedure should be performed for any modification that affects the intake or exhaust.