I'm not familiar with Speedworld and don't run Associated anymore but I can give you some helpful tips.
First off I would choose a good set of tires. Afterall tires are 80% of your entire set up.
Get one of Maifield's high bite indoor setups to start with and practice, practice, practice. Try to find out how the truck is reacting and start making small changes one at a time. Only make one change at a time, practice and check lap times, if you are consistently slower change back, then practice some more and make more changes. There is no perfect setup for everyone, you have to adjust to fit your driving style.
With Gearing someone might chime in on that. It's a good idea to get a temp gun and check temps after 2 minutes of hard running anyway. With the power of brushless and lipo, gearing is pretty much for safety so you don't overheat your stuff.
Let me know if I can help you with anything else.
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