Rusty Dusty

Hey there and greetings from Poland! I have a 2002 Tahoe with a LM7 under the hood - a truck I like so much, that despite the fact I bought it to haul my recreational/sport stuff, it pretty much ended as my daily (spring till autumn). I have read somewhere (and kinda confirmed it just a few minutes ago on Youtube) that the post-facelifting trucks ('03 and newer) are faster than pre-lifting ones. I mean 299 vs 273hp and 9,0s to 100kph (62mph) vs 12,0s. My Tahoe really does the 62mph in a pathetic 12 secs. And now the question is: how to make a '02 truck as fast as a '03 one? What were the changes? And how did they manage to cut off a whopping 3 secs by adding just a small amount of horses? It's only 26hp more. Is it only tuning or is it something else? It would be nice to get a bit more in return for feeding this always thirsty V8. Cheers!