Factory tire pressure setting is for stock suspension. Now you go aftermarket suspension. Not sure what your tire pressure setting. I usually lower tire pressure on my rear tires for stiffer aftermarket suspension to get better ride. You may also need to adjust your tire pressure...
Thanks for advising. I'm not using the stock tires anymore so the tire pressure is based on test runs and adjustments. Different tires also vary a lot, it could goes from 34 psi (Michelin PS4) to 27 psi (Bridgestone S007A)for the same size.
But yes, stiffer suspension suits lower tire pressures, as mentioned.