The Lightning2 is a tuff little buggy, I've abused one for a couple of years and now, rebuilt, it is my sprog's ride. And she can drive it better than me.
I think the shocks are a bit weak, and Hyper 7 shocks with white springs seem much better, filled with 40 f & 35 r they handle our bumpy track well. The C cups can break easy(ish) if you run into tyre markers, or similar, too often
Most of the Lightning pro stuff, knuckles, chassis braces, seem fine. The HB .26 engine is fine, but not the fastest, as you say. Try the Go .21 7 port (£120 delivered from MK Racing). It flies! Make sure you have the hardened diff gears though, and fill the diffs with decent oils, 5k, 7k, and 1k as a start. Might like 3k in the rear though with the extra power. Enjoy it, and give the Hypers etc a good run for their money
You'll need a 6v hump pack, like a Venom or Nanda one, won't break the wallet!