The stock inlet is a sure bottleneck for our cars,aproper ported plenum can increase airflow by about 20%.If you have a larger throttle body then you can port match the TB to the inlet by scribing the diameter on the face of the inlet and remove the material to about an inch in on the inlet.You must funnel the transition on the inlet, the wall is not that thick so you need to blend in the new diameter so as not to go thru the inlet wall.I believe that the stock inlet is good for about 65mm without making modifications to it.I am working on one now for a member it all depends on your goals.