i have a Tunit one on my JK diesel, cost me £400 including setting it up in there workshop with a lap top. very happy with it, and its adjustable. then once set up you can remove it in 5 mins, ( for servicing if your truck is under warranty) and put it back again afterwards. don't know anything about the cheep ones. frosty
Wks read in imperial gallons not US as long as the body control module is configured for UK market.