I did change the box on the side exits on my S3 Matt, but if I was going to change now I would definitely go for the Aero SS twin-pipes. I'm sure that Boshers will be along shortly as he has had the twin-pipe conversion done at the factory on his S4.

Cheers
Brian

P.S. Hope to see you as usual on the way to LMC! woohoo

Brian

1970 Morgan Plus 8 - Moss Box (Indigo Blue)
2014 Morgan SP1 (Rocket Red)
2015 Morgan Plus 8 (Rocket Blue)