QUOTE(rfuerst911sc @ Sep 15 2008, 04:41 PM)
There are basically two schools of thought on batteries. Some folks like traditional wet cell batteries and others like dry cell. I personally like the dry cell batteries for several reasons. For one they do not leak battery acid so that is a real plus. Also "generally" the dry cell batteries will be lighter in weight than the wet cell. And dry cell supposedly give longer service life but they tend to be more expensive. The main two players in dry cell are Optima and Oddysey. I have a red top Optima in my 911 and I just purchased a Optima D51R for my 914/6. However you have to get creative to make these batteries work in the standard battery trays. Hope this helps you out.
I'm also an dry cell fan. My current red-top Optima has been in the car since 2003, never a single problem. No issue cranking in the cold or anything. It's not light, though. There are lighter dry cell offerings, if that is important to you.
If going standard size, you may want one of Triad's $26 Optima battery mount (very high quality piece), to properly fit/secure it in the 914 battery tray:
http://www.triadwestperformance.com/Products.htm(Triad West Performance is an amazing company, btw - highly recommended!)
Good luck.