Toytec may have your answer. I just installed their Superflex coils and longtravel 5100s. They gave me an extra inch but have yet to settle. I hope they don't! I've been running their 1.5" spacer on top of the 891s for a year or so. No problems, just not up to handling my 300lbs of permanent cargo. Got my fingers crossed for the Superfex's and Bilsteins.