After almost 3 months of trying the BB springs vs the std AE springs, I personally am faster with std. The easiest way to describe the difference between the two is that the AE springs feel more darty and precise, while the BB springs all tend to make the car feel more plush, maybe a little slower reacting and they land rough jumps better. If you still want to try for yourself, here are the parts needed.

Parts needed for Losi Big Bore Spring conversion

RPM spring collar #70322 / Traxxas version #3768 (use either or)

TLR Front 12m spring , silver #5174
TLR Front 12m spring, orange #5173
TLR Front 12m spring, red #5172
TLR Rear 12m spring , pink #5168
TLR Rear 12m spring , yellow #5167
TLR Rear 12m spring, white #5166

TLR 12m spring cups #5095

GHEA Spring Collars (very nice)
part number - GHEA2070

Available at Absolute Hobbies or directly from GHEA overseas.
http://www.absolutehobbyz.com/produc...9r5s7jpfvbqqn1