Bunkersparadise.com wrote an article about DeChambeau's driver that can be found here:
In addition to removing weight from the head the driver also has a JumboMax XL grip that weighs a whopping 121 grams vs normal grips at 50 grams. This puts even more of the weight away from the club head.
As many know, I do not use swingweight and prefer MOI measurement (total club MOI) to determine the heft of the club. Although B-9 is very light, but not all B-9 swingweights are the same. Also, the theory that adding weight to the grip will create a lighter feeling of heft is very misguided which is where the biggest flaw in the swingweight measurement resides. It does not account for the total weight of the club and therefore it is saying that a club becomes lighter when you add weight to the total mass.
I tried the JumboMax Grips on my 3-iron a few months ago. The JumboMax grips are exactly like they sound, they are far larger and heavier than your standard grip:
One of the interesting things I found with the JumboMax grips is how it actually increased the MOI (made it heftier). I had my 3-iron set to 2,725 MOI with a Pure Grips P2 Wrap model. Adding the JumboMax XL and the MOI shot up to 2,755 MOI.
What we know about swingweight is that adding 10 grams to the grip will change the swingweight by roughly 1.5 points. So with a 70 gram difference between the JumboMax Grip and a normal grip, the swingweight would roughly be at D-0 if there was a regular grip on the head. And with the difference that the JumboMax grips make on the MOI, it's a 'heavier' D-0 swingweight. Still light for a Tour player, but not actually as light as the B-9 swingweight implies.
The big thing about Bryson's driver is that static weight of the club should be rather heavy. I play my 45-1/2" driver at 2,825 which is at about D-4 swingweight (relatively heavy). The static weight comes out to 318 grams (203 head weight + 50 gram grip weight + 65 gram trimmed shaft weight).
Bryson's driver should come out to roughly 375 grams.
180 gram head weight (estimated, we'll say 198 grams is Cobra headweight and remove the 18 gram weight)
120 gram grip weight
75 gram shaft weight (estimated after trimming)
So perhaps with the JumboMax grips, Bryson may have needed some weight taken off or he would have close to a 400+ gram driver.
Also remember that Bryson utilizes the JumboMax grips as he grips the club in the palms. And when you look at his swing, it does not have much wrist-cock in the backswing.
So perhaps with a club that is as long as the driver, the weighting has to change in order for him to feel comfortable due to his grip in the palms and less wrist-cock in the backswing. Either way, Mr. DeChambeau keeps it interesting for sure.