Obviously there’s a lot of variables, and it is probably more correct to talk wheel rates, but for an aggressive street/occasional track setup how much stiffer than stock would you recommend for spring rates before fine tuning with ARB? I’m thinking relative stiffness to stock and ratio of front to rear as the mechanical differences in coilover design will change the literal number somewhat. Thinking typical fast street tire setup such as 215 or 225 front and 255 or 265 rear re71r or similar.I've written about ARB's a lot. The main challenge is to actually make them work. Leverages are very long, the travel path is very short, only a few cm when the suspension travels, so that's why there is no major difference in terms of body roll whether you run stock ARB's or not. What stock ARBs do is mostly suspension bind and it is bad. GMS ARBs will bind the suspension too but at least they will prevent body roll. So we need stiffer torsional ARBs with the least possible weight. We have the solution on a way. Still I suggest ARBs only as an fine tuning element. First tune your spring rates, otherwise the suspension binding will increase, weight will increase, inner wheel spin will increase, nose dive and squat will remain unaffected, only body roll will decrease. ARBs should primarly be used for fine tuning understeer/oversteer balance, not for masking other suspension problems. Don't look for shortcuts, there are none if you want to do it right. 🏁
Seems like most of the available options are somewhere from 1.2 to 2 (3 in some of the race specs) times stock rates and from .6 to .75 ratio front to back.