sooo i just bought a g8 now what to do next.....

[I12XLR8]

What is the free bass mod?

The stock amp has a gain control that is set to 50% from the factory. A quick twist of the dial gets a bit more kick out of the subs which you might not need now if you've got an extra 10"

.....and I got the car for 19k..

WOW! Sounds like a great deal!