Shock oil sounds a bit light, the car seems to like heavier oil (the worlds setup sheet says 600cst without tyre additive!)
I wouldn't expect the kit springs to work in low grip so it's good that you're getting the HPI set, most run silver/silver, pink/silver worked well for me last year.
You don't say which shell you're using, I couldn't get the ltc-r to work at all, went much better with Speed6. I know most people run the ltc-r outdoors, maybe I got a bad one, but I had no forwards traction with it at all.