Our most powerful LS-6 head for 3.900" bore!
Package includes:
Disassembly and cleaning of castings
Removal and installation of larger valve seats 
to accomodate oversize intake valves.
Fully CNC port intake, exhaust, and combustion chambers
Competition multi angle valve job.
2.055 Ferrea intake valves and 1.57 Rev exhaust valves
Mill heads to customer combustion chamber specs
Flow intake and exhaust ports (Sheet included)
Assemble heads and set all spring heights and pressures 
using Dual gold .650" lift springs,aftermarket cups, 
titanium retainers,and gm seals.
Other spring options are available please call
Can be built for use on 4.00" or 4.125"bores.