best Neu for speed

[VintageMA]

Are you planning on running 4S or 6S?

6S I would go with the 2D.
4S I would go with the 1.5D.

You could easily gear into the 50-60mph range with ~40-45k rpm. You said you wanted speed runs so I assume you want faster than a racer. I would also get the 17mm wheel adapters and run with the HPI Phatline tires - great on-road tires for a truck because they are so low profile.

If you are going to running Zippys I would go for 6S/5000mAh to keep amps and temps down.