That may be a little low but sounds about right. THose 4:10s and 235s cant help at all. Your rpms are way high while cruising. If you want it to be better you could change to 3:73s but would sacrifice some towing power.
A forum community dedicated to Chevrolet and GMC diesel truck owners and enthusiasts. Come join the discussion about duramax engines, performance, builds, modifications, classifieds, troubleshooting, maintenance, and more!