Aftermarket B-Series Intake Manifold’s improve airflow and increase horsepower by as much as 8% to 25% depending on build or your modified aftermarket intake over stock manifolds on stock engines and even more on modified or turbocharged engines. There are a number of intake manifolds that significantly increase horsepower in ranges of 2700-9200 RPM’S the larger plenum’s and tapered runners and gutted out runners like a Skunk2 or a jdm styles are best with turbos or a custom aluminum boxed intake. They Increases Acceleration and Airflow. By Porting or Enlarging the intakes Air volume inside the intake you can increase the effects of wave scavenging at the Motors Maxximum  RPM range. Providing a hard overall increase in usable Power. Each runner port should also be matched to balance and not Restrict airflow between cylinders. Bigger bore throttle bodies are a must to add to a new manifold. In order to v-tec proper you must change and make a safe tune always remember to turn off ignition advance when tunning.