And also, MAKE sure they are checking the piston to valve clearance(with the clay method and a micrometer).....you don't wait to see if the valves are hitting the pistons to find out things are too close(damage is done if that happened, NO DOUBT).....Ya know, That's probably the "serious" noise they first heard when they started it up, and "NOT" a (unlikely) cam bearing comming loose, and now they are making up lies and excuses since your good "expensive" heads probably need to come off for having bent valves or worse(THAT THEY CAUSED), but who knows now, just my thoughts.............they should have checked this during the build (right "before" the heads were "permanently" put on) and they should be able to tell you an EXACT figure for what the clearance is for BOTH your intake valves, AND your exhaust valves.....as long as you have aprox 80-100 thousanths on the intake Valve side, and 100-125 thousanths on the (hotter) exhaust valve side....this range of valve to piston clearances is MORE than safe on an LT1.........also, only in situations where the LT1 block was decked, a thinner head gasket was used, "AND" the heads were cut a bunch does the LT1 intake manifold "NEED" to be cut......some shops like to go ahead and shave it the mathamatical equated amount for what was changed (IE: block, gasket, shaved heads, Ect...) and thats good too... but most people after performing these EXACT commonly done mods were talking about here, are able to "EASILY" get away with just "slightly" slotting the intake manifolds bolt holes(and many "Like Mine" don't even need that done for it to line up perfect)...and your head port to intake port alignment should be fine as well.......god... this is really basic stuff that they should know , especially if they have any business working on someones car...no less a corvette....and, shame on them for lying to you about ALL this, which they "certainly" are.......and as you know , I "MUCH" prefer Lloyd Elliotts or Advanced Inductions Cylinder Head port work over Proflow jakes stuff that you got from Ebay(no real comparison)......but as I told you, I have seen many of his (proflow jake) heads in person, and installed a few sets as well.....and they "all" went on just fine and performed pretty good as well.......and "Just" like your cylinder heads in your pictures, the other sets of his heads I've delt with were just lightly skimmed as well, "just enough" to give a nice clean even head gasket surface......always remember... when you see an LT1/LT4 head with that indent area still present "above" the exhaust valve(like in your pictures) you know the head was just skimm cut....that area dissapears after "aproximately" 30-40 thou of a cut(sometimes even less).........Joe