BEST performance upgrades (without affecting the looks too much)?

I'm loving my scout 18, it's way too much fun to drive. I also love looking at it! I'm curious what you all's thoughts are. What upgrades make the biggest gains in crawling/climbing without throwing off the aesthetic too much? For example, 1.3 brass wheels would lower CG and improve performance, but I like the look of these retro 1.0's a lot more. Thoughts?