RX8 Setup

Hi, Just have a few questions obout some of the settings on the RX8 Unit.

I am currently running a Tekin 1700 Truggy motor on 5s 5800mah.

I am lacking a fair bit of top speed down the strights.
Gearing is all correct.

So the questions are:
The Timing profile, When using the hotwire, it tells me the default setting is C2.
You can choose from C2,C1 then from 5 to 1.
Am i best to leave it at C2 as I can't find anything that really tells me what the other settings are designed to do.

The other question is the timing function on the hotwire.
(the start and end rpm)
the default settings are set at:
Start 5,443 rpm
End 20,016 rpm.

Am i best to leave these as they are or increase the end rpm up a bit?
It lets me set the end rpm up as far as 40,000rpm

Any information on these would be greatly appreciated.
Thanks.