With your Durango? I bet you aren't gonna see any mpg gains (no offense, just stating the facts).
Sorry to rain on your parade but given such type and weight of vehicle operating under LA/San Fran in Ca, you ain't gonna get any mpg gains out of it.
I was down at SF 2 yrs ago and got stuck at the bay bridge traffic (friends live in San Jose) for 3+ hrs and little to no movement whatsoever. Yeah, you may say that you are trying to make your vehicle more "fuel efficient" but a V6/V8 idling give you 0miles/gallon and that's the sad part.
Like most other posters here who responded to your postings before: you have to make a decision whether the Durango is worth your while.....
Just my contributions to the subject. I do tow a trailer with my wifey's Camry Vee6 every once in a while for construction and camping purposes....and that makes our V6 worth keeping. YMMV of course
