The guys above have done most of the work for me
thanks guys.
I decided to run 4+2 as i can run a lot lower C of G, what you cannot see from the photos of the S4 is the chassis is milled so the centre slipper / motor mount is as low as you can get it in the chassis. Remember that a motor is 177grams or over 10% of the total weight of the car so i feel its important to get it low.
Also on a early prototype slim4 i had a 4+4 cell layout to test weight distribution further which was interesting
The S4 shell was designed to accept brushless speedos with fans on top, Chris runs the TC spec LRP and this fits easily in the S4.
Now back to Solidworks and work on the S2.