I had a 06 GT and bought the ford racing intake. After just about 10,000km the filter looked like it saw 100,000km - and I look after my stuff, keeping it clean. I know they're popular with the "aftermarket performance" guru's but after everything I've read and know now I think they're pretty much show pieces. You will benefit more from just a tune with the stock airbox than adding a crappy completely exposed air filter. NO, not everyone will agree but have fun spending your money (wisely)!
Only sales people and hungry hungry hippos will go on and on about how AMAZING the difference is with this INSTANT power adder. It literally adds 5-10hp MAX and your ass will NOT notice that difference. And I firmly believe that they don't filter air as good as a airbox does. I looked in my inlet tube two years later and the ford racing paper filter was deteriorating, I could see dust and other smaller particles on the inner sidewall of the intake tube. Total garbage. Looks wise, yes, great, it's "cool" that you can rattle off all the things you have done to your car...tune intake exhaust but when you lay it out flat, it doesn't amount to huge changes in performance.
After you buy the intake, go to the track and do some runs stock, then with a tune, then with a tune/intake combo. You will gain "maybe" .3-.5 seconds and of that improvement, 99% of it will be from the tune.
Not everyone agrees with me on this but you'd be better off putting your money into suspension components than an intake. The tune is important, the intake not so much. Alot of it is hype. I'm in a 2012 now and run just a tune and I'm sticking with the stock airbox. I'm sure the engine will thank me for it later.
It is better to remain silent and be thought of a fool, than to open your mouth and remove all doubt.