Lightweight Battery

[force44]

What are people using for race batteries? I need a lightweight & low cost battery for my Boxster as my next weight saving task?

There are some on ebay from £50 -> http://www.ebay.co.uk/itm/120930891229

or the smaller Oddessy 25 or Varly 25 ones are £100-£150

Are these big enough to start and run the boxster without any issues or needing a recharge over the weekend?

many thanks

Garry