I have driven cars with front & rear AEM kits and really like them.I have a Wilwood front kit(upgraded pads) on mine and have found some problems while stopping in the rain.I'm hopping my troubles will go away when i get my AEM rear kit installed to balance my front to rear.
Wilwood are lighter then stock brakes(@12 Ibs).If money is an issue you will spend less with the AEM kit.There isn't a huge difference between the two kits.
As i see it,fast brakes uses rotors and/or calipers from other cars.( this is how it seems with dom. cars anyways)
upgrading your calipers will also improve your braking.