Land Rover Repair: Powerchip, power, MPG, To good to be True?, octane fuel, old cars

Question
Hi John, I came across a forum and a guy said he installed a Powerchip brand chip in his Discovery I, and was getting impressive results. Increased power and torque and best of all an increase of about 2MPG. 15mpg in the city. The  question is, have you had any experience with chips? Does this lean the engine to save fuel? The price is about $500.00. For the amount of driving I do I would be willing to pay that for 2 mpg and a little more power. I always use 92 octane fuel. I do not rev the engine to the maximum like my old cars. I don't want to chip it if it could cause engine damage.
My Discovery has been very reliable so far. I found out I am lucky to have a coil sprung model. The rubber flex-coupler is going out and causing vibration under acceleration, I will be replacing that soon.

Thank you,
Willie

Answer
Hi Willie,

I don't have one in my '95 - no need.  As for newer DI or DII, it may give you some additional power but is that worth $500?  For a 2mpg gain, keep your money and pay the extra gas.

An other owner wrote: "it changes shift maps and fuel maps coorespondingly, as the D2 ECU set up is too rich".  

Most only noticed the difference while passing other cars.

Regards,

JohnMc