There are multiple paths that you can do for exhaust. You can go with a full system, you can go with a "custom" delete of some sort, or you can go with a downpipe, or all of them.
There are a couple of systems that are available, theres the IPD system, the ELEVATE system, the BORLA system, the Snabb system and there is the KT4 system. The IPD one has some nice depth to it, but still keeps it nice and quiet. The ELEVATE one, is a louder/raspier sounding exhaust system, and Borla one is the same. I don't really know enough about the other two to tell you valuable information about them.
Now for a custom delete of some sort, you can do a muffler delete, resonator delete or cat delete. Now unless you are really looking for noise, I don't recommend deleting the muffler. The muffler on the P3's is big, and it does a lot, by deleting it, you can cause an increase in noise and some drone at higher speeds. If you are looking for some raspier tone to it, and not a big increase in noise, I recommend you delete the resonator. Surprisingly, when you delete the resonator, it doesn't increase the drone. Unless you are looking for a fartcan type sound, I do not recommend that you delete the cat.
Now for downpipes, there is an IPD one, KT4, and Ferrita. The IPD one is a great catted option, if you are not looking for a massive increase in noise, get the IPD one. The KT4 downpipe, in an amazing downpipe!! I have it on my XC60, and I highly highly recommended. The KT4 one comes catted, and catless. If you are looking for LOUD, get the catless one. Depending on where you are located, the Ferrita one might be the best option. The Ferrita downpipe comes straight from Sweden, and very very $$$ due to the all the shipping and the manufacturing from Sweden. People have said that the Ferrita downpipe is a very loud downpipe, and that it comes catless