This is the result of testing and tuning on my b4.1 worlds with big bores for the past few weeks. This setup uses softer springs than the common 'team' setups and instead relies on roll center modifications to counter act the lighter initial damping of the 1.6 pistons. The goal of this setup is specifically to stay on the 1.6 pistons and reasonably light (especially front) springs. I feel that many of the stiffer spring setups are stable but not as capable due to less front/rear weight transfer and that the 1.6 pistons deliver the most benefit of moving to a bigger bore shock.

Pistons
The big bores with 1.6 pistons and the same weight oil have less damping but more pack when compared to the old shocks. You can see this yourself by bolting an old and new shock together at the eyelet and just playing with them.

If you go up a half weight in oil, the 1.6 have more damping than the old shocks period, both normal damping and pack. You can run the 1.7s with thicker oil and get basically the same regular damping speed and pack as the old small bore shocks, but then what's the point of going to big bores if you can't get more pack for big jumps paired with lighter initial damping to float over bumps better. It is my opinion that the 1.6s are the right piston choice, really bringing the benefit of big bores home.

More roll with 1.6 pistons
The lighter damping causes the car to roll quite a bit more than with the old shock setups. This is immediately apparent when you try to run brown front springs and black rear springs, basically the old shock spring rates (old rear green == new rear black). In my testing and tuning, I determined that at 24mm ride height, even with a shaved u-brace w/ no washers and the a-hubs, which offer a higher roll center than the c-hubs, I could not keep the rear from rolling too much and washing out in the rear at times, especially when coming out of corners.

Chasing the front and rear with stiffer springs
I tried a few rear spring and front spring combinations and settled on green rears and black fronts, which allowed me to get roll centers working, but the car was just less capable than my old v2 setup and felt like it was lacking front/rear weight transfer due to the stiffer springs required to tame roll. It was a decent setup, but it was a bit loose, and a bit pushy. On a high bite track, it was great, but as the traction surplus went away, I was at a disadvantage compared to my old setup. I decided to go back to green rears and brown fronts and try everything I could to resolve the roll issue without increasing damping and the rear becoming loose too easily on corner entry. I briefly ran 23mm in the rear, and it worked well, but it took away a bit too much on power steering, and I knew it could be better.

Raising the roll centers
After extensive roll center tuning, I have determined that the issue with running the green springs in the rear and the car wanting to come around in corners had a lot to do with the front roll center being too low and rolling over, not the brown springs being too soft and transferring too much weight forward. After tuning the rear roll center at 24mm with ball stud washers, I went to the front and went to the outside ball stud location on the tower with zero washers. This is the lowest possible roll center setting available on the current b4 platform without shaving down the front tower risers (note that they used to be lower, allowing even higher roll center options. Luckily, it got the job done in our huge banked sweeper and completely cleared up any lack of corner entry traction in the rear. It is worth noting that, unlike the rear, you can move out on the front tower and shorten the camber link without worrying about camber rise because the front end is far more affected by the caster blocks in corners and the forward traction of the front tires under deceleration when pointing strait is not even in play in a 2wd because there are no drive shafts.

I did extensive wet/dry soft dirt track testing tonight with this setup and am very pleased with the current state of the car.
Wayne