As previously seen,

https://hackaday.io/project/176214/log/212713-propdrive-dreams

 the cheapest way to get more speed was seen as creating a modular nose cone rather than expanding the motors, using hotter windings, or expanding the battery.  The nose cone had to be field removable without tools, stowable so the leash could be accessed, & not cover the headlights.

The 1st step was converting the headlights to a narrow strip.

Various nose concepts followed, with cardboard, coroplastic, & PLA.  After many miles, the best performing one was 3 sided with permanent string holding the bottom & a removable string farstening the top to the truck.

Ideal speeds with a nose cone:

#    dist    sec    min/mile
1    213    43    5:42
2    201    44    5:45
3    203    44    5:44
4    208    46    5:49
5    201    46    6:3
6    211    44    5:51
7    205    46    5:52
8    208    44    5:53
9    206    47    6:0
10    204    45    5:43
11    211    43    5:42
12    200    44    5:47
13    203    46    5:58
14    306    70    6:6

Typical speeds without a nose cone:

#    dist    sec    min/mile
1    208    48    6:9
2    305    73    6:24
3    405    98    6:28
4    408    103    6:43
5    404    100    6:35
6    404    100    6:34
8    400    101    6:45
9    407    110    7:14

Speeds with a nose cone were highly variable, depending on weather, payload, wheel alignment.  Without a nose cone, it was guaranteed to have a hard time getting above 6:30/mile.  With a nose cone, there was a possibility of it getting above 6:00/mile.

There's no correlation with the number of sides of the nose cone.  A 2nd nose cone on the back might buy it more speed.

The latest nose cone is glossy & collapsible.  It rests on the bumpers while clearing the leash.