reLentless, how would you recommend following that up then as white? Obviously, at this point, you're going for black's king, as unless you checkmate black or get a lot of material in trying to kill black's king, you're going to lose.
King's Gambit, why not played at master level?

My answer to the initial question:
"Because today's top GMs are in fact patzers compared to Chigorin, Spielmann, Bronstein or Spassky."
The fact is that Boris Spassky as champion checkmated the best computer in 18 moves without serious effort, while current top GMs aren't able to draw vs Rybka.
Thus - today top GMs are much weaker players than Spassky was and because KG is very skill-intensive, current GMs are unable to play it.
You may argue, you may disagree with me, but that is all you can do with that.
What a load of bollocks.
I'm sure he's joking.
Yes, i was joking a bit.
But more seriously: KG is my main weapon against 1. ... e5. I used to play Evans, but i had problems against Two Knights, so i switched to Ruy Lopez (Spanish) with KG as backup for possible surprise. But i switched it, because KG seems to me stronger, sharper and more logical than slow Ruy. I play Ruy only against "weak" players to avoid any risk when i expect to outplay them anyway, or when i expect my opponent is prepared to play some minor variation.
If theoreticians and top GMs think KG is unsound, because black can choose between equalising without any risk and taking the risk, i disagree with them.
1. e4 e5 2. f4 exf4 and now 3. Nf3
Bishop gambit 3. Bc4 is interesting, but black responds with 3. ... Nf6 4. Nc3 c6! with next d5 and gets slight advantage.
3. ... g5 ancient move, still most used, but i consider it dubious.
4. Bc4 I preffer it over 4. h4.
Now black has two ways: 4. ... g4(?!) and 4. ... Bg7(!). The first way leads to Muzio. Muzio gambit is one of the mysteries in chess. White sacrifices whole piece for positional compensation. Black kingside is destroyed, white gets center, f-line and attack. There are ways for both sides, computers fail in evaluation. Some people think Muzio is forced draw. Not, because white has at least two ways how to avoid it and play for win. The second way, however, is much harder. My current opinion is that white keeps full compensation for a pawn.

Hammerslag, you miss the point entirely, when playing against black, you have options of play that can force draws easily and although every game should technically draw, the Evans offers too many draw avenues I understand that I am insulting part of your repertoire but the higher you get the more you will find that other openings offer more ripe positions ...

In my patzer point of view, if Topalov can get away with the Nxf7 sacrifice against Kramnik's Petroff, the King's gambit should be playable at the highest level as a surprise weapon. I'm counting on Ivanchuk and Topalov for that.

Furthermore, I´ve sat there picking out some very interesting ideas for black players and lines that I think would help a lot of players who havent necessarily played against the Evans g and regardless of source the examples follow classical lines ie. after c3 Ba6, or Bd6...

I think the reasons are multiple. First off, white has to deal with tons of different responses from black, either going for equality or the advantage (black only has to specialize in one of these lines). Second, it's not a good try anyway for the advantage and all the tactics are much much less likely to work on top players than on amateurs. With that said, I haven't seen any grandmaster games that clearly refuted it, but it's also hard to argue that it's better than the normal options for white.

I believe the reason you see so few GMs playing the KG as white is that there is too much risk involved. A GM with white doesnt usually want to play risky lines, with few exceptions.

Another recent King's Gambit between two GMs.
Ha ha! that Rook really tore up the open board.

i think there is a basic jrobichess vid with kings gambit where he goes through it and at on stage he has fritz on infinate time kepping spacebar down and black never seems to hold out

http://www.chess.com/tournament/c37-kings-gambit-accepted-rosentreter-testa-gambit-expirament-1 its themed 4 1.e4 e5 2.f4 exf4 3.Nf3 g5 4.d4 g4 5.Bxf4
I enjoy playing the King's Gambit, and recently realized that few masters and (to the best of my knowledge) no grandmasters play it. I was wondering why that is. Is there a line of it which is unsound?
The sac you showed is pretty sound, but you didn't play the line correct. The point of "most" sacs is to achieve superior positon via hyper development, wereas you did neither since you yourself violated the first rule of chess...moving the same piece twice (in your case three) times in the opening.