and a warranty that fits your thought on how long you will have the car.
https://sites.google.com/site/mikefocke2/batteries has a list of ones known to fit.
A "Porsche battery" is nothing special. Nor is installation. If you have ever done one on any car, you can do it. Only trick...put battery into trunk...climb into the front trunk..now install in place. (and have your radio code card or number handy).