LS1

Chevrolet - GM LS1/LS2/LS6 4.8L, 5.3L, 5.7L & 6.0L
Performance level - Stage 2 - Excellent mid & top end performance.  Requires ECU tuning.
INT/EXH - Dur @ .050” Lift: 226°/231° RR: 1.7/1.7 Gross Lift: .607”/.617” LSA: 118° 

Chevrolet - GM LS1/LS2/LS6 4.8L-7.0
Performance level 2 - Increased flow or Aftermarket head required. Requires ECU tuning. Good Valve to piston clearance.
INT/EXH - Dur @ .050” Lift: 217°/226° RR: 1.7/1.7 Gross Lift: .553”/.575” LSA: 110° 

Chevrolet - GM LS1/LS2/LS6 4.8L-7.0
Performance level 3 - Great choice for bigger displacement engines. head work or aftermarket head required. Requires ECU tuning. Check Valve to piston clearance.
INT/EXH - Dur @ .050” Lift: 230°/238° RR: 1.7/1.7 Gross Lift: .600”/.5612” LSA: 110°