I recently wrote the Wikipedia entry for the Austrian Attack, maybe that will come in handy. Unfortunately I already returned the book to the library, but the article does contain an illustrative game from Spassky vs. Fischer 1972.
How exactly do you beat the Pirc Defence?
I always play 1.e4 d6 2.d4 Nf6 3.Nc3 g6 4.Bg5 against the Pirc proper.
I did have a recent tournament game against the Czech Pirc (3...c6) which continued 4.f4 Qa5 5.Bd3 e5 6.Nf3 Bg4 7.Be3 Nbd7 8.Qd2 with advantage to White.

Data Pillar's Queen sacrifice is excellent (comment 14). Chesslab stats give it 61% win to white, 23% win for Black and 16% draw. I wouldn't call it a sacrifice but an exchange. White wins three minor pieces for the Queen! material may be even but three pieces are far better than one. Black should absolutely not accept the sacrifice.

I have played this 1000 of times with friend, who has all the games. I can give you some great games at the beginning of September :) He's not available before :)
By the way, to everyone, do you know how "Pirc" is pronounced?
Not like "Perk" but like this: CLICK

(Btw I just looked at the OP's name and realized that he might actually be me after all these years.)

I play the Pirc, and from what my opponents try against me, I think just attack the kingside immediately, or don't let him get the center. Do both! My opponents have played to excessively attack the pinned knight before.

Okay, I'm pretty sure that Pirc is not pronounced "Click."
Hahaha, I can't put the link in 1 part, so I set a link in word "Click". :D
I m a pirc player myself...i have played it a numerous times and have had a good success as it improves your positional understanding,piece play and manoeuvering skills!...against f4..i would recommend the pirc players to play the Gurgenidze system..that is e4 d6 d4 g6 Nc3 c6! f4 d5! e5 h5!..the setup for black is..d6 g6 c6 d5 h5 Bg5 Bxf3 Nh6-f5 OR Ne7-f5 Nbd7 Qb6 c5 0-0-0!!!...Although it is equal but you have more plans than in normal austrian pirc lines...u ll not sit around defending white's attacks...ur central night on f5 will help u to great extent!! c5 also helps u to get a break on queenside..dont move ur pawns on kingside..convert the play to queenside and keep ur king safe!
The Pirc is a counter-attacking opening - so trying to blow it out of the water early on with a reckless pawn advance (as often seen in the 150 attack) is pretty much what Black is hoping for.
Instead, why not play a system that is quieter, safer and doesn't give Black much to aim at when he/she tries to counter?
I find a great little system is 1 e4 d6 2 d4 g6 3 Nc3 Bg7 4 h3 Nf6 5 Nf3
Move order might be different, but it's important to play h3 before Black can play Bg4.
The move h3 might look like a waste of time - but time isn't really much of an issue since Black isn't exactly developing at warp speed. Critically, it does two things - it prevents Black's light squared bishop developing to a decent square and also prevents the annoying Ng4. This latter point is especially important because pretty soon White will put a bishop on e3 and possibly the queen on d2. As for White's light squared bishop, wait until you've worked out Black's development plan before deciding where best to put it. Bc4 is sometimes possible, but Be2 (keeping the bishop out of the way of Black's queenside pawns) is played more often
I'm not saying you'll get an overwhelming advantage, but White's position is easy to play, and you won't end up in the type of mess that makes you regret ever moving that f pawn...
I think the Austrian Attack giving White more space with the central pawns is the best answer.
Mikhail Botvinnik remarked that he felt the Pirc Defense was actually stronger than the King's Indian Defense. In some variations (like the Averbach variations) there are similarities. Botvinnik had played the French Defense his entire career, so he was not in a hurry with the Black pieces. I find the way I play the Pirc myself that the game is too cramped as Black to suit me. I prefer 1. e4 c5 and just play the Sicilian Dragon and skip the Pirc entirely.
The Modern/Pirc/King's Indian defensive system is kind of an Anyman's defense, not bad because Black does not usually waste time getting castled. The positions are similar and the whole complex is easy to play. Most Anymen just skip the King's Indian and make their defenses 1. e4 The Pirc Defense and 1. d4 The Modern Defense. 1. c4 no problem. This style becomes second nature to these players to the point that they skip the openings in favor of the middle games, so long as they do not become too cramped.
In his book 200 Modern Chess Traps In The Fianchetto Openings, J.B. Howson has 27 pages on the Pirc Defense. I notice in most cases White has won the games. Therefore, we can conclude most of "the traps" are in White's favor. Another way of putting it is that White has the opening advantage, while it is Black who must avoid the pitfalls. It still remains for White to translate his advantage from the opening into the middle game (positionally) to win. In cramped positions it is more difficult to spring winning combinations. Defensive combinations are all that is possible until the endgame.
Two things happen here. (1) White can push too fast and become over extended because of impatience. (2) It gives Black the opportunity to keep White's knights away with a whole series of defensive pawn pushes. This is pretty much of an overview. I do not see the Pirc Defense as all that dangerous. Black is simply hoping White's man o' war will run aground on the reef.
The question remains, " How exactly do you defeat the Pirc Defense? " The answer to that question is: that the Pirc Defense has not yet been refuted.