Excellent gains, and from what I have researched on the web, pretty much the most gains out of all the available kits for our trucks.
Here's Magnaflows Dyno, for the same setup type of exhaust:

Gibson: can't find info
Corsa: can't find info
Borla: can't find info
Flowmaster: can't find info
If anyone else can find Colorado/Canyon specific information for gains, please post them, so we all know.