I highly recommend the SCT tuner with custom tunes. They custom tunes will be created specifically for your car and will give you a better performance gain, compared to a canned tune. Just my 2 cents.

 

You don't need mods for a custom tune to provide significant gains. Even an 87 custom tune runs circles around the 87 octane stock tune.

 

Not sure if the gains are similar from the 4.6 to the 5.0. But on my 08. I had the ability to dyno the car stock, with a k&n intake, and then again with a BBk intake and tune. The k&n yielded ~5 hp over stock and the BBk w/dyno tune yielded ~17hp over stock numbers. All done same day same dyno within 1.5 hrs of each other

 

I thought I heard an intake for the new 5.0 netted near no gains without a tune, but not sure if one would with a tune more than the stock box?

 

It would depend on how the 5.0's airbox breathes. On the 4.6L, the CAI adds about 5 RWHP over a standalone tune.