The only thing I find with the 1.8T engines is you don't get any low down power, although I've not tried it with a remap to be fair.
I suspect you'll find an all-round smile-burning increase with a remap, and if you want the extra traction, you'll want to upgrade your Haldex controller too. I'm not on commission I swear (although some of the uk-mkivs lot accuse me otherwise ) but they are awesome bits of kit [y]
500-550 for the controller, and I gave it to AMD to fit (just under an hour) cos I'm a wuss 
In theory it's a ramp-up the car, unclip cables and unscrew the little box from the bottom of the car and replace. You'll prob need a small bottle of haldex oil in case you drop any, although fi you've got it off you might as well do the oil change whilst oyu're there.
I leave fiddling with cars to mechanics, and I stick to IT