RPM arms (although, most don't have issues with stock), lunsford turnbuckles to allow for easier adjustment of toe-in, HPI big bore shocks look to be wicked good, but running 8 stockers with 40 weight should get the job done.
Really the only weaknesses on the savage are the diffs, center axles and slipper.
Gear too tall and the slipper likes to slip and glaze up on you, which means you may gear a bit lower than you'd like and have less top speed. I think I'm running 15/49 at the moment with an LRP28S3 in it. The engine could pull more gear, but not without locking the slipper down. I tried 15/47 and within a tank, the slipper was a slipping on take off even when it was barely backed off 1/8th turn. I may be running 16/49... but can't recall.
The diffs for the following reasons had issues with blowing out. My guess is partially to blame the slipper since most lock it down due to slippage. That combined with cast gears vs CNC'd and plastic spider cup adds up to weak diffs. Also, the case the diff was in would flex. Most of that was fixed on the X/XL by redesigning the case, milling the gears and adding an alloy cup.
On my savage, I'm running X/XL diffs with alloy diff cases to keep the gearlash perfect all the time. My only real remaining issues are diff input cup wear on the centers and the slipper thing. Neither of which stop me from beating the snot out of it every single chance I run it.
