There are many holes to be drilled into the three skins of the forward fuselage. Be sure to have plenty of sharp drill bits on hand as they will become dull drilling into the 4130 steel. SPA recommends cobalt drill bits and that is what I ordered from McMaster-Carr. Still waiting for them to show up. I wore out three of the standard drill bits they sell. Sure hope the colbalt bits last a lot longer. I clecoed the fuel line tunnel and the six floor stiffeners into place The tunnel cover will stay off until I have the engine mounted and my fuel lines run.