Re: 156 v6 muffler on 2.0?
If you're talking about the 2.5V6, then not a problem at all, except for point 1 below.
If you're talking about the GTA V6, it is possible but will require a bit of work.
1. First off, the inlet pipes are different diameters so you'll have to put a 'step-down' to get the pipes to fit properly.
2. The exhaust pipes will also stick out a bit further from the bumper, which looks a little odd, but should be okay if you have bodykit on the rear.
3. You might also have to adjust it to sit higher on the mountings since I believe it sits lower on the GTA.
As for the sound, my 2.5 v6 now has a nice little growl to it. Not loud like an aftermarket, but a little more presence. For this reason, and the difficulty in getting the pipes to fit properly, suggests that it is not the same part as for the other models.