Feuling Velocity Stack For Harley Engines with modified and ported cylinder heads, coupled with larger throttle bodies and enhanced intake systems, deliver remarkable boosts in both horsepower and torque . This makes them an excellent choice for individuals seeking exceptional performance, whether for racing or weekend track outings. Features: 3 tall high flow billet aluminum velocity stack 4 opening with internal taper down to 62mm ID Natural aluminum finish stack Backing plate available in black or chrome finish Made in the USA