Great idea!
Note: just to install the BATTERY without the cutoff switch, you probably need only remove the post-adapters from your positive and negative battery cables. Lotus has configured the Elise / Exige different ways, to check to see if your post adapters are bolted to your positive and negative cables. If so, it's easy. You may need to drill the lug holes a tad larger, or they may fit as-is depending on what Lotus used that day.
Here is the parts list for adding the cutoff switch:
DelCity
5413 Cutoff Switch ($21.90)
412605 12" Lead Battery Cable ($2.27)
917655 Copper Compression Lug ($1.38)
900905 Battery Terminal Solder Slug, 4 Ga ($0.XX)
**EDIT** You may not need all of those part #'s, look at your OEM setup. I updated the 12" lead part number. **EDIT**
Watch the soldering video on the DelCity website to see how the solder slug works. It's pretty cool.
With shipping and everything I can add this kit for $33.00 or save a few bucks and source the stuff yourself. They give me no price break on quantity orders
