Fdr ratio help

[Lordslimjim]

I have multiple charts etc I have found on the net for which combos pinion and spur gears to use on my sakura sfor and they are all about the same

The q I have is just basic what do yet all mean

I presume a lower value lets say 2 fdr give a faster acceleration than 6

But 6 would have a higher top speed?

I'm planing on running a 13.5 t motor and currently have the parts to run a 6.2fdr what would this achieve (sorry if it isn't making much sense but I am lost)

I haven't seen the track I plan on running so not sure if its a short technical etc its Telford hot trax if that helps any1