With all the chatting about the front diff that just sold I would like to learn some more about them.
The two questions I have are:
-Which type of LSD is the best from track type driving
-What order would you suggest upgrading the diffs in?

There are 2 threads worth of diff talk stickied, on tooners that is a good read.

And if you want to learn about different brands etc, evo123.net is a good place to start. they seem to be more into that stuff.

Cool, thanks Mike!

I read let's talk diff thread a few time on tuners. From what I got rear diff is the first upgrade, and the bets handling mod according to some, one should make. As stated it provides a more neutral balance to the car (less understeer) and really helps to throttle steer and rotate the car around corners. The two other are a bit more complicated... If you upgrade the front in theory the center diff shouldn't work as much. The only problem I have found is the most popular front diff offered are 1.5 or 2 way as kaaz and Quaife. This produces off throttle understeer which is really counter intuitive ( imagine arriving at a corner a bit to fast, letting go the throttle and suddenly bam understeer the car can't turn) . The ideal front diff IMHO would be something like what was recently sold here...:( a 1 way meaning it's locking on throttle only. Center LSD diff are usually even more expansive and arguably could be the last one to be upgraded. Not sure that helps.

I'd do the exact opposite.
Centre first because they are weak and will shatter if you make any real power.

Front, because stock is open.

And then the rear, since we already have lsd rears. swap the rear to an evo diff or something to make the car swing around corners.

Both of that helps a lot. I am rolling around on a 3 bolt rear right now so the rear diff will be the first upgrade I do.
Right now it's just deciding how far I want to go with that upgrade.

I do agree with the first part of your statement, I was kind of assuming his centre diff was already upgraded to a 4 spider which remains an open diff but is much tougher if he is putting serious power. In the end it all depends on what you do. For a drag car, first would be welded centre diff than 4 bolt LSD rear (viscous) than front and lastly rear clutch type LSD (like Evo 3-8). For a car that sees lapping IMHO I would do a rear 4 bolt with upgraded max lock LSD (Evo 3-8 + upgraded clutch plate) first or centre (4 spider) depending on power goals and lastly the front.