RE: Large packs... Check this out!!!
The motor is a 200hp (150kW) AC induction motor, custom made for Kent, the thing is actually big enough to probably push 300+hp if he had a controller to push enough juice... I think the batteries are about maxed at 200hp though... so you'd need more added in parallel.
Kent is amazing with carbon fiber and composites! He actually owns a business that makes custom motorcycle fairings! Wish I could remember the website. There's lots of pics of his work, it's very nice! He even has a carbon fiber breifcase he made for himself and it looks like some fancy store-bought case.