umm upgrade the rotostart to a pullstart
Seriously I found the rotostart to be pretty bad, and ruined a few of my bashing outings when I had it. Was way more reliable on a pullstart
Outside that umm if the rear knuckles give you trouble the Integy HD uprights are pretty decent.(yes I said Integy, and decent in the same sentence) My X has no issues with the rear knuckles, but the .25 I turned into a flux the rear knuckles the tierods kept popping so I went the integy route.
One note last HPI engine I had the factory default settings were WAY too rich to break it in as my engine only hit like 180 degrees( i only remember it cause it was so low) on a hot summer day. I had to lean it out to get it up to the proper temps.