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I would go back to your to your base line then maybe add 25lbs to the rear springs and play with rear shock settings for the added down force from the wing. The roush track pac cars are 515 lbs front and 400 lbs rear springs, with the little wing it has. The rear shock valving is stiffer too.
Are you using the anti-squat brackets ? I removed mine after the torque arm install and it improved the balance by a lot. But I'm running a funny set up right now myself. 500 lbs front, 200lbs rear with a Strano adjustable rear bar on soft. Using the JRI singles, I'm using 24 clicks front...