fitted my new copper plugs what difference does re gapping from .8 to .7 actually give does it effect power etc over rev range?

 

Bigger spark=hotter spark

Hence why mapped cars require a smaller gap to be a bit kinder to the cylinders and allow for the spark to be more consistent through the rev range as heat can dissipate more effectively. As we found in a recent thread the platinum and iridium plugs are made for longevity and spark pretty cool, but don't dissipate their heat as effectively as the copper core plugs. The copper cores however are supposed to last about half the time as upgraded plugs, but are a better conductor. I'm kind of repeating what was said in that thread now but basically if the spark is cool and well conducted you'll have more consistent and efficient ignition through rev range. As far as mpg and power goes any gains or losses will be pretty marginal. It's more about drive ability and efficient ignition. Of course this enables the mpg to be where it should but it's more about the gap and the material than the brand. Upgraded coils (2.0tfsi for example) also allow for cooler ignition, which in turn enables you to run a bigger spark and give the ignition a bit more punch and still be kind to the cylinders. It's a pretty complicated business.

That's my basic understanding although I'm sure someone here has a more technical answer.

so 2 litre coil kit stock gapped coppers would work?

I believe so, going by what I've read on that basis. You can always change the gap and experiment with it. It may help the coppers longevity to reduce though. To be honest though that's only based on what I've read, I don't have first hand experience. Think there's a lot of talk about uprating coils on other vag forums. Give Google a blast.