You need to research more or have those that run 4" SL chime in. For those that run Rocky road shocks, not too many are impressed with ride quality, hence the low price. That 4" trailblazer kit doesn't include extended bumpstops, which are extra. It states 4" OME coils with spacers ? doesn't state what size spacers and why ?. At 4", I think a SYE/DS is recommended. I have a feeling you will end up needing way more than that $800 kit advertises.