better CAI and catback 11 A3 2.0T
 

Is the K&N typhoon intake and a magnaflow or borla catback system a worthwhile power investment and will it need tuning?

Depends on what you're looking for. Aftermarket CAIs and catback can help boost the power of your ride. I have the AFE stage2 in my A4. Bough it because of the deal I found at http://4wheelonline.com. I like the sound of this intake and had no issues so far. But if you really want a noticeable gain, get a custom tune.