J & J's Speed Shop's CNC ported LS3/L92 cylinder heads start with brand new GM castings

• Custom Stainless Valves: 2.16" / 1.60"
• Volumes: 269cc intake & 100cc exhaust
• Flow: 343cfm @ .600" / 242 @ .600" (4.030" test bore)
• 75cc combustion chambers - milling available
• Patriot Dual Extreme Springs
• Hollow valve upgrade available