I found this on GAF just now:

Wait, let me change that console estimate: I predict that MS will sell 16k units in the TWO weeks after Forza hits. The third week is Trusty Bell. That will blow up the 360.

umm none. Forza 1 didn't sell well at all in Japan, why would Forza 2? It's not like the 360 has done any better than the xbox in sales.

Forza was competing head-to-head with the GT series at the time. That's not the case anymore.

And the 360 is doing considerably better than the Xbox in Japan. The Xbox launched to a big lead and then faded to nothing. The 360 is doing the opposite. Of course, sales are still crap compared to other consoles, but when compared to Microsoft's last attempt, the 360 is improving.

And BTW, I believe Ridge Racer sold around 65k copies for the 360. There's no reason Forza can't do a little better, especially with Famitsu giving it a rating like that. 

Very little impact, less than Blue Dragon.

Considering that when speaking in percentages, Blue Dragon had a large impact on 360 sales, that's a pretty vague statement. Here's the charts... I'm sure you can figure out when Blue Dragon launched for the 360.

http://www.vgchartz.com/hwcomps.php?cons1=XB&reg1=Japan&cons2=X360&reg2=Japan&cons3=XB&reg3=Japan&align=1

Before Blue Dragon, the 360 was moving about 1k a week in Japan. It was completely dead in the water. Now it's merely on life support.

Are racing sims big in Japan? Sega did F355 for the arcades / DC but I suspect that was targeted at western audiences. It will make a big impact in my house when I try to figure out where to put the Wireless Wheel ;)

All I found on VGChartz was the original Gran Turismo for PS1 but it sold 2.2m copies in Japan.

That was so long ago though... I suspect Japanese tastes have changed since then. Look at the relatively low sales of TP in Japan compared to Oricana. I doubt Forza 2 will shift many 360s in Japan but it won't do any harm. Personally I can't wait for it. Great demo.

Sim racers are pretty friggin' big in Japan.

The GT series is pretty big over there. Ridge Racer 7 has sold around 125k units on the PS3. RR6 on 360 has sold 72.8k, and is the 3rd highest selling 360 game in Japan. There are alot of factors that make it very difficult to predict where Forza 2 will end up.

Factor 1: Forza 1 didn't have alot of exposure in Japan. This can translate into a meaningless brand name (but for that matter, BD didnt have a brand associated with it, nor Dead Rising, or half of the major selling 360 games).

Factor 2: There are no major racing games to compete with. Motorstorm is long gone and dead, and so is RR7 for PS3. With no racers coming up, Forza could fill a huge void. Only TDU is the most recent racer out there.

 Factor 3: This game is the finest racing sim ever created (ever play Forza 1? Far better than GT). If Famitsu gave it a 36/40, thats pretty dang good.

Factor 4: With Trusty Bell coming out merely 2 weeks afterwards, with quite a few projected new adopters for the 360, they could pick up Forza 2 as well.

Forza is a TOTAL toss-up. One one hand, it could do as low as 40k. On the other, it could nearly topple, or beat BD due to the obvious lack of next-gen racers. TDU is upto 20k, and that's a friggin' budget title (incredibly good game tho).

Range given: 40k (10% chance) upto 250k (10% chance). I'll go ahead and say 95k based on the following factors: The game will launch with sales of 52.5k or so O/W, drop to around 20k the week after. When TB launches, it will manage to hover in the 5-10k area for awhile. It's anyones guess as to how it sells systems. I'll put Forza in the "major system seller" catagory of which N3, Dead Rising, DOAX2 and DOA4 were in. It will move around 15k systems over it's lifetime. 7k first week (nearly beating, or even beating the PS3), then maybe 6k next week before TB takes over. But again, it could be the "thing" like the BD/LP combo we had in Christmas, and manage to move 50k-100k systems along with TB, or better. It's possible. It's also possible the sales only spike to 3,750 units too.