if you want to actually keep the motor and esc cool...
19/90 on 3s with stock tires will net you about 37mph. it should be fine. but depending on outside temps... you'll still want to keep an eye on things.
The following brands of Lipo's generally have good reviews for general use:
The C rate: you want to get as large a pack as you can justify to spend the money on.
I am making an assumption, but if you are talking about 3s, it sounds like you have a VXL???
If you are in fact running with a VXL system, I'd try to get a lipo pack that has at least a 150Amp rating.
To calculate the Amp capabilities of a general pack: Multiply the Cap (in Ah, not mAh... just move the decimal to after the first number. so a 5000mAh pack is a 5.0) by the "C" rate.
so a 5000mAh 20C pack is a 100Amp pack... (5.0*20=100)might be a bit weak.
but a 4400mAh 40C pack is rated for 176Amps (4.4*40=176)
A lot of guys like to run a 5000mAh 40C pack.
My Tastes are simple:
I am easily satisfied with the best.
-Sir Winston Churchill