Well first, if the supplemental result obviously means a bit less interest from Google, it does not mean your content won't show up in the search results.
It usually means that Google does not see any urge to massively crawl these pages, and that the content is few or poor. It's the case for example with threads where many images are posted but only few lines of text.
So, besides working on writing detailed articles that should not end up there, you can work on making your page as light as possible for guest, to increase the content's weight.
As well, url such as -http://www.buggynews.com/aftermarket-oem-parts-off-road-go-karts-mini-buggies-vf6.html could be a bit shorter and better targeted, it can help out, and it's SEO wise harmless to edit the forum title with the zero dupe
An occasion to work on you site's content I'd say.
The title optimisation mod will for sure help out, but I don't think it will be the one to raise all your pages out of the supplemental result. I think this is more content (text and final html code) related, since your forum is already really well SEOed code wise.
Working on backlinks should as well help out, 3 is really few