[Patrick]

In my truggy I've used my 1515 2.5d on 3s, 4s, 5s, and 6s. I usually raced it on 5s geared for ~35mph. I like that setup.
I've raced it a little bit on 4s when there was a 4s battery limit (stupid rules), geared it up a bit to get similar top end to 5s. Worked pretty well, bit less punch, but still enough if you don't need the fastest car to get good times.
I kept the same 4s gearing and did some practice laps on 3s. I'd say it was about the same sort of speed and acceleration as the titans on 12 cell nimh, with much lower temps and more runtime.
If the 1y is too much then the 2.5d should be enough, there's also the 2050kv 2d which is kind of in between the 2, just gear it to the speed you want.