Slash 4x4: race upgrades

So you want to race a Slash.  Well, assuming you have a stock Slash 4x4, the most important upgrades are:

• Low Center Gravity (LCG) chassis
• Proper tires
• New shocks/springs
• Faster servo
• Center differential
• New body with vents
• Good ESC/sensored motor
• Good radio
• Rear swaybars

The LCG chassis is the most important, you can’t even use the traction sticky tires will provide, without it.  Tires are always key, and decent suspension is necessary to get the car to handle at least halfway acceptably.
The stock servo is super slow and the plastic gears will break.  A new servo will amaze you with how much faster you can control the car.  A center diff is necessary to get the car to be more agile.  For those of you new to short course trucks, the first thing you’ll notice is how much a stock body parachutes when jumping, so a vented body is pretty important as well just to get the car to fly OK.
Obviously a new motor will help with power and a decent sensored ESC will help with being precise with that power application.
After that, you start getting to tuning preferences and control preferences.  With some of these basic upgrades, your Slash will at least be tunable and have reasonable performance.  After that, it’s really up to you to set up the car to drive best for your local track.  The stock plastics are fairly tough and stiff, so you don’t really need to get aluminum this or that (wheel hexes are the exception IMO).
Until you get more experienced, getting the correct setup for your car will be more important than any other upgrades.