Originally Posted by jhbrennan

The Optima 34R will fit (but you'll need to modify the hold down). Looks like the suggested Odyssey battery for the 997 is an odd size too - it's a Group 49 whereas the 997's take a Group 94. I've had great experience with the Bosch AGM H7 - perfect fit, good specs and warranty plus you can usually find a pretty good coupon if you order on the Pep Boys web site and pick up the battery at a store.

https://www.pepboys.com/product/details/838845/00797

Originally Posted by SoCal C2S

It's a group 94R...and you may have to modify the battery restraint...$248, free shipping in the lower 48.

Originally Posted by jhbrennan

Which battery are you talking about? Odyssey website shows this for the 997's:

ODYSSEY Extreme Series Battery Model PC1350
(Group 49 (Euro L5) with automotive style posts)

Any 94R (H7) battery should fit in the 997 tray with standard hold-down.