I have both mufflers. There is very little weight difference. Take a flashlight and look inside your muffler. The touring version has about 6 inches of a screen like baffle on one end; the other end will have open slats about 3 inches from the end. Sport muffler has a little sreen on one end only. Here is my estimate of noise levels; on a scale of 1-10.
Stock muffler: Idle-1; WOT-3
Corsa Touring:Idle-3; WOT-5
Corsa Sport:Idle-5; WOT-9
No interior drone with either Corsa muffler. Hope this helps.