It depends on the battery you buy and your battery holder (assuming you don't have a 3.2 with the battery in the trunk).  Unfortunately Audi changed the battery holder several times during production.  The result is that some TTs require a battery with specific notches in the base.  The easiest way is to remove the battery first and check its base for notching, if any, and then get a battery that matches it.  Otherwise, you may have to file or dremel the notch yourself.  Many folks will say they used this or that brand and it dropped right in but what works for one persone will not always work for another.  The Sears "international" line is one that many (but not all) find to work well.

Thanks for the useful information.  I have an 02 TTC 180.

Previously vegasroadstter wrote:

It depends on the battery you buy and your battery holder (assuming you don't have a 3.2 with the battery in the trunk).  Unfortunately Audi changed the battery holder several times during production.  The result is that some TTs require a battery with specific notches in the base.  The easiest way is to remove the battery first and check its base for notching, if any, and then get a battery that matches it.  Otherwise, you may have to file or dremel the notch yourself.  Many folks will say they used this or that brand and it dropped right in but what works for one persone will not always work for another.  The Sears "international" line is one that many (but not all) find to work well.

I replaced the battery in my 2002 Coupe with the Sears International. It fit fine, but there are three things to watch out for: 1, you don't need to disconnect the wiring block on top of the battery, just disconnect the battery at the terminals and move the wiring block out of the way. 2, the new battery was just slightly shorter than the old one, and I had to cut a notch in the side of the battery box (just half an inch) for one cable. 3, have your radio code ready, and know how to use it, or you'll be begging the dealer to unlock your radio for you!