Not sure on this particular car, but looking at it on the website, it looks like one bad machine!! i kinda want one...
Some more info would be needed on the gear ratios in the car to findout what would be needed to attain 100mph..
Im damn close to 100mph in my SC8E with a 2200 kv motor, 6s battery, and 23/44 gearing
How close too 100mph are you right now on 4s?
Also, id be careful with the suggestion of smaller MAH batteries, these will have a lowered ability to provide sufficient amperage, makes the possibility of puffing, or blowing a lipo much easier.