Welcome to the site. Steer well clear. You always get what you pay for. I think this is little more than an intake temperature adjustment.
Here is something that jumped out of the page at me:-
Do not be fooled into purchasing a cheap 2p resistor as pictured above
(if the item you are purchasing has NO picture of the actual product then it is more than likely one of these, they are cheap rubbish that will cause lasting damage to your car if used for any length of time, and should avoided.)
I notice that if the picture above is not of the product then by this guys own admission "it is cheap rubbish!" He's covered his back with this statement and if you buy you will have little or no recourse.
If manufacturers could spend a few quid and make the car run better then they would fit this sort of thing at the factory.
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I got complimented on my driving today. There was a little note on the windscreen; it said 'Parking Fine.' | 
VARIBLE BOOST CONTROLLER 
Linear Mode
