It really depends on the situation and track and what you mean by "grip". Focusing on the rear, lowering the roll center (raising the stud) almost always produces more low speed grip, but can reduce grip when going on power or leaning hard in a corner. Likewise, lowering the stud (raising the roll center) will almost always add the ability to exit a corner harder, but it can add excessive rotation or "slide" to low speed operation.

What constitutes more grip for you depends on your track layout and what you need. On a open fast layout, adding a washer, as you have stated, will definitely add more net grip, but on my track, which is small and tight, the b44 platform can suffer at the apex of very slow corners when the rear unloads a bit and over rotates, and removing a washer tends to help out way more than hurt high speed corner exit.

To summarize. On the B44 platform, if you have a lot of "almost stop and turn" corners, removing a washer might be best, but if you're on a larger "high speed" track where you keep the throttle on more, adding a washer might be best.

Shock oils, ballast weight size, and washers are my primary tuning attributes when track layouts change. Ballast weight first, washers second, then shock oils (especially if the washer change really jacked up the balance of the car).

Wayne