[Locobob]

That's excellent Steve, glad you are happy with my work. Headers, exhaust and intake porting really work well together - each compliments the other and you'll only see the full potential of each when combined. From my dyno experience a little knock retard in the 4K range is pretty normal and hard to eliminate, if it doesn't recover quickly or comes on in the higher rpms then I'd work on your tuning some more. 12.5 should be plenty safe for A/F.