If your grounding straps are properly connected, your system will work as well as it is spec'd out. There is no magic "grounding" for better performance, only proper grounding that makes the electrical system perform as it should. With that being said, if your ground connection was bad, fixing it might seem like it helped, but you won't improve over original performance. Think about it, if a thicker cable made more power, Volvo would have been all over it for performance and efficiency.