321 Stainless Holy Header 2-BoltHH 2BOLT The Killer B Motorsport Holy Header was developed using state of the art CAD software & simulations to determine optimal design to increase power as much as possible throughout the rev range. Short as possible primaries with a single secondary significantly decrease header volume allowing exhaust gas pressure to build quickly. Symmetrical 4 1 design maintains high and consistent exhaust velocity as RPMs rise. You can expect faster spool up