LRP 8.5t motor 'final' ratio question?

[Dr_UpGrade]

Hi Guys,
This 'may' be a silly question, and if so I'm sorry... However, here goes:

I've recently bought an 8.5t LRP to go in DEX210. The blurb that comes with the moter suggests that this motor works best in a 2wd offroad with a final ratio of 8.5:1... No problems there, I can use a 26tooth pinion on the std 87 spur on the dex to give a final ratio of 8.7:1.
I'm using a hobbywing/bullistorm controller with the settings RogerM suggested a while back of:

boost timing =10
TURBO timing = 18
Turbo delay = off
Turbo ramp rate 3deg/1000rpm
Turbo start revs = lowest

Now my question is with these type of settings is the LRP suggested final gear ratio still valid? Is the moter 'still' behaving like an 8.5t or is it now more like a 7.5 or 6.5? I'm swapping out from a 6.5t where I was running 21:87... I'm a bit concerned that 21 to 26 is a big no' of teeth and I dont want to cook my speedo and/or motor..

Sorry this is a bit long, but all opinions gratefully received...

Cheers!!