So I took my 2011 SX in for it's 45,000km service on monday through a Mitsubishi dealership and was surprised with how I got my car back. I have a custom exhaust but that is about as far as "Performance" mods go on my car as well as running 98 octane. As I drove out of the dealership I noticed when I planted my foot my car would have a extremely deep exhaust note (more than usual) between 3k-4k revs whilst being slightly louder throughout the whole rev range.
I also felt that my car had a lot more power under acceleration which by no means I am complaining

What are peoples thoughts? I love how my car sounds louder now and has more power but would like to know what they exactly did to achieve that?
- Mits.