I recently put a new battery in my '01 Base and in investigating them in the Porsche parts system, noted that Base gets a 70 ah battery and S gets (maybe it's can get) an 80 ah battery.
'mericuns don't seem to deal with amp-hour ratings but best I can tell
Group 48 = H6 = 70 ah
Group 94R = H7 = 80 ah
I determined this with the chart here:
http://www.eastpennmanufacturing.com/wp-content/uploads/Deka-Exact-Fit-Flyer-0379.pdf
The Ford (!) dealer where I bought my Boxster had installed a group 91 and when I replaced it with a 94R the holddown screw went into the threads one step to the right (side of car) of where they were previously.
Deka, BTW, has the contract to produce BMW-label batteries for USA BMW dealers and they are good stuff.
Bosch has nothing to do with production of PepBoys batteries other than licensing use of the name.