Sixpackgut has always run 6 packs on his challenger (493" RB motor), but he did test a GOOD single 4 setup once and it slowed his car down. If I recall correctly he tested an Indy single plane w/ a 950 HP Holley against his well tuned six pack setup. He is not using a stock six pack intake though. When he did the test I can't remember which 6 pack manifold he was using, it was either the Weiand SS hi-rise 6 pack or a modified tunnelram with a six pack top on it. CHIP