However, if you go with 4" tube, then you will have to reduce it to the size of the throttle body as it enters there and that will cause some stacking at that point and should keep the velocity up there.
That exactly why my intake came with 4" ducting.
2004 Impala LS - got some mods sold!!!
2009 Subaru Impreza WRX STI
NAIOA moderator Still Imp'n, just in a different Imp.