install a Chip or Don't insall a Chip ??

[GOPAPA]

That is my question
I bought a 2006 Chevy Duramax , and just took a 1000 mile trip...I have owned the truck for a year or so now and in town it gets 15 mpg or less ,,so my question is should I install a chip to help me pout pulling a travel trailer

This is what I got with "out" towing a travel trailer ..made a mistake and said with a trailer..so I edited it correctly

I got 18.75 mpg a going and coming back I got 19.6 mpg

I kept the speed at 62mph as close as I could both ways..

I was told that if I put the edge chip in my truck I would get 6 more miles per gallon @ a cost of about $400

Is these chips really worth it ? and will I get the 6 mile extra like I was told?

I searched this out on this forum but couldnt find my exact questions //