Whats the deal with that varipower thing, why would you have it on anything other than 10? Is it for people who are too lazy to move their right foot (but will happily twiddle their knob for hours on end)??
I don't think i'll have full acceleration today Mr Sulu, I'll set my car on gas mark, er, i mean warp factor 8 instead. WTF??
Steer clear dude, it's one of these characters making a happy little living conning gullible chavs out of their hard-skived in return for highly questionable gains to the pulling power (in both senses) of their Paxo 1.1... yeah man wicked cool, i got this k&n, straight through exhaust, chipped, powerboost resistor kit, superplugs adaptor (how the hell is THAT supposed to work? magically pulling energy from.. where?), halfords spoiler and underlighting..... gotta be at least a 50bhp power gain man innit.
Besides if you really want to do it you can get the exact same damn thing from Maplin for about 20p!
Its been seen on this board a good few times the trouble that incorrect fuelling (from broken temperature and lambda sensors) can do for your engine, and one of these basically initiates that exact same state. A small increase in fuel mixture richness over the usual economy/emissions-dictated stock setting CAN give some power gains, SMALL ones, but you're unlikely to notice the extra few percent kick in the back or two tenths of a second off your 0-60 as you would the increase in fuel consumption, exhaust stink, and quite possibly lumpy running, especially when warm. Also as the resistor is unlikely to be specialised to your car the chance of overdoing it - and actually losing power/responsiveness due to running far too rich - is just as likely as getting it spot on.
As is the chance of either cocking up the install and having the ECU reject the readings as a "broken sensor" because the circuit is cut - or just rejecting them anyways even with it installed perfectly - and switching into get-you-home failsafe mode... which will give you about 30bhp and 15mpg as it pains itself to keep the engine running without knackering it.
PS
This was supposed to make the spark plugs stronger and burn more efficiently... not sure if it worked well...
Between VW having spent several million deutschmarks* conceiving, developing and refining their original type watercooled engine over the past thirty odd years, and a whole lot more revamping it into the mk4 polo version..... and some geezer on a motorshow stand selling you a mysterious item to "improve" the spark and combustion (the spark plug only sets it off, remember... and you only see an improvement with "performance" plugs/coils on high end engines like the G40) backed up by nebulous claims .......... which are you going to trust and believe?
*i can never spell that ruddy word
anyways if you deside to buy one, get one for me to. I gota try this.. 
hehe..