Yeah not sure on the stock wattage there, however why are you curious about this?? I am just thinking you may be gauging how good the speakers are off the wattage....?? Anyway, I am going out on a limb here by assuming thats why you are asking and if I'm correct (hopefully) I would say that is a bad way to judge. They very well could be 8 as was said above. Stock speakers are designed for 1 purpose, maximum performance/sound quality with as little power as possible being used. Now, best quality just means the best you can get for $5.00 or whatever it cost them to produce the speakers. However factory speakers usually are very efficient with decent (arguably) sound. That's why most factory speakers use paper cones, less power to move the cone. Also, if the speakers require less power the deck can be made to produce less power. It's a big scam see, a way to save money.
On a side note, another scam is how much a deck is said to put out in power. For example, most alpines claim to do 60x4. I think most other companies claim like 45x4 or somewhere in that range. Anyway, thats not important because whatever number they say is bullshit. I read in a car audio magazine once that when tested the most that any deck put out was like 12 watts or something like that. I believe it was a pioneer with the mosfet chip. But it makes sense if you think about it. Look at the size of a common 4 channel amp that puts out like 250watts total. Thats about 62 watts per speaker if you have 4 hooked up. Yet somehow an Alpine deck is able to hold all of the memory functions, the cd player, the BBE technology, the radio receiver, and produce almost the same amount of power as a 4 channel amp that is built for one purpose and is twice the size?? Doesn't add up right? Thats because the car audio industry isn't as tightly regulated as the home audio industry for some reason. Basically if a home audio amp claims to produce X amount of power it has to be able to produce that amount of power continously. If a car amp makes the exact same claim it just has to be able to produce the claimed amount in a lab somewhere once. So thats why you end up with 2000watt amps made by Kenford or Rockwood (actual names, they took ken from kenwood and ford from rockford and mixed... how creative) that you can buy for $40.00 bucks. Perhaps when they were testing the amps a bolt of lightning struck the lab bench and they got that reading, who knows. My point is, don't believe what most companies say a speaker is rated at or what an amp or deck are able to produce. They are liars. Listen to your ears.