Is this it?

If I was to run a 120mm Rockshox SID ultimate on the front of this, would I want a 42mm or 51mm offset?  The description says 120mm front travel, the geometry table says 100mm front and 506 AtoC and says 51mm offset.  If I add 20mmtravel/extend AtoC, do I want to change offset? 

I think by lengthening the fork I'd slacken the headtube by ~1° which would lengthen the Front Center and also increase the trail.  shortening fork offset would also lengthen trail/shorten wheelbase I think? Lengthening trail increases wheel flop, makes things more stable at high speeds straight ahead, but not as quick steering?

What makes you think it requires a trunnion mount shock?  It looks like a regular 6.5" X 1.5" shock to me.

Upon further review it looks like it could run a regular or trunion mount shock if it's the same as the 911.  Someone on a different forum had recommended the lcfs911 and said fox 165x40mm trunnion mount shocks can be found cheap on ebay.  I took that as only trunnion mount would work.  I'm new to this and still learning so I apologize for dumb questions and really appreciate everyone's help.

First impressions are confirmed. This is a fun and fast bike.

The 120mm on front gives a noticeable bit more comfort compared to a classical 100mm XC and at the same time i keep an agressive position due to negative stem and short headtude.
I wanted to test a long reach with short stem (50mm) and i really like. The steering feels natural, the grip you have when you lean the bike is so nice
and due to low handle bar i don't suffer of slow steering at all.
Once you understood you can trust the front wheel this thing rides really fast. In fact it's like having a right sized bike without the front wheel just under the hands.
At the moment i don't see why going back to "traditionnal geometry", except the fun of riding a twitchy bike?

About suspension i can confirm that the fox evol works very well, in normal use i don't need to tune something or put volume spacer, the travel is well exploited.
On easy terrain, if you really like to put the hammer down, the fully open mode is too soft, firm mode is better or open mode with the hardest setup. The top is surely to get a shock from a scott spark with the 3 positions remote.

To end, a fews things i have in mind :
I don't see any reason to use a 100mm fork, the bike feel greatly balanced on 120mm.
Even if i could also ride a smallest size frame I don't regret my choice.
Keep in mind too the seat tube is steep so it's not for people who like to sit on the back.
If you want a cheap boosted XCO bike, don't hesitate.


Someone asked if this was the next level, probably yes!

Do you think a 2.35 tire on a 29 or 30mm ID wheel would fit in the rear?  the Steven's model in the linked story looked like 2.25 Barzo that might fit tight.