Core shots are usually repaired by first applying a foundation layer of Metal Grip (a mixture of polyethylene and heat-sensitive adhesive that adheres better to fibreglass and metal than normal P-tex repair material) to the exposed core and then filling the rest of the hole with the P-tex repair material of your choice.
P-tex repair materials are not made of sintered UHMWPE like P-tex bases are, as it's not possible to heat sintered UHMWPE to its melting point without changing its molecular structure, so the repair materials are made of softer extruded PE. Drip candles are the softest, p-tex string is about as hard as extruded base material and p-tex repair ribbon is the hardest (almost as hard as sintered base material) but it's harder to apply.
Alternatively you could use a 2 component methacrylate adhesive, such as this:
http://www.bondrite.co.uk/structural-acrylics/methacrylates/black-medium-cure-thixotropic-acrylic-50ml/prod_120.html just fill the hole proud, leave it set overnight and file / scrape it back to the level of the base.
The construction of top quality skis has changed remarkably little since the Blizzard Firebird era, although shapes and flex patterns have obviously changed enormously. They still have sidewalls and wood cores that are sandwiched between layers of fibreglass and in some designs aluminium alloy and they are still laid up by hand using a 2 component epoxy laminating adhesive.
http://www.youtube.com/user/TheSLsport#p/a/u/1/uPRW60ek1AY
http://www.youtube.com/user/TheSLsport#p/a/u/0/SbwYTjDhI-0
A pair of 160cm Gotbacks weigh 3.38kg whereas the a pair of 163cm Auras weigh 3.20kg which is a surprisingly small difference when you take into consideration the extra with of the Gotbacks, perhaps it's because the Gotbacks don't have any sidewalls or metal in them and the core is made from soft woods instead of hard woods.
