😛 If you want a better sounding exhaust, get the cat back. You generally don't need a tune for a cat back. If you want more power, with a better feeling power band, get the AP.
If you get a down pipe later on with a cat back, you will need a tune. Which is why I said get the AP. If you get a tune now, with no turbo back, you will need one later. (extra moneys). If you get the AP, you can use their stage 2 map when you get an exhaust later.