the compressed rear suspension can be troublesome over bumps whether its been modified or not. i’ve heard the same is true for the new Si as well. changing the ride height can be a b*tch due to the way the suspension is setup both front and rear.
fortunately i will be keeping mine completely stock as well for as long as the warranty lasts. that’s sad too because i bought the comptech rear sway/tie bar kit for it and the kit will sit in the box until the warranty goes…in 2012. only thing i’m going to get for it is some nice summer wheels and tires.