There's a few easy ways to make your car louder
- buy a petrol
- Fit a k&n panel filter
- I'm sure there's a stainless exhaust for your car
- Have you local mechanic remove the rear box and weld a length of pipe in it's place
-Have your local exhaust outfit make you up a one-off stainless exhaust
- Remove the undertray and engine top cover, drive with windows down
Hope this reply is better than a few of the suggestions above
