I would recommend good electronics and tires before anything else. I wouldn't suggest running the tires that come with the F.T. kit, they are junk (the rear Subcultures are ok, but didn't work at all on my track). Tires make a HUGE difference, and getting ones that are designed for track conditions similar to your local track, will give you a significant advantage. Also, a servo like the Savox SC-1258TG will make a big difference.

However, if you are looking for upgrades beyond that, I'd highly suggest the Avid Aluminum Bellcranks. They are a one piece design, so you will get better response with your steering. Also, the RPM chassis and front bumper kit is a popular upgrade for the truck. It will add much durability to the truck's front end. However, if you are a decent driver, and don't wreck a whole lot, then you may not need the extra durability. Another cheap, but helpful upgrade, are the RPM heavy duty rod ends. Also, picking up a pack of lead weights is a good idea, and will allow you to dial your truck in a bit better. Another thing I did, that made my truck much smoother, was to replace the thrust balls in the transmission. The F.T. kit comes with carbide balls for in the diff, and they work great. However, the kit comes with steel thrust balls. I switched them to ceramic balls, and it made the diff feel much smoother, and last longer. I HIGHLY recommend using this RCTech video guide for assembling your ball diff. If you follow it, you will have a butter smooth diff everytime... guarantee it!

One other thing I would say, is if you are planning to install 12mm hex adapters, you may want to consider upgrading the rear hubs to those that are on the AE B44. The reason being, is that the B44 hubs have the same inside bearing as the SC10 hubs, but the outer one is larger and will not blow apart as easy as the outer SC10 one's. If you are looking to do this upgrade, you will need to buy AE B44 rear hub carriers (or an aluminum B44 rear hub carrier), 1 set of the AE outer bearings, and 1 set of the AE crush tubes. As for the inner bearings, you would reuse the inner ones from your SC10 hub carriers. Hope that helps