There have been very few cars in the past 50 years that have been simpler and cheaper to mod for more power.  If you Google the pony car/muscle car era, you'll find cars like the Hemi 'Cuda, Boss 429, GTO Judge and more that couldn't touch the power of the 2007 Shelby GT500. The 'Cuda, for example, featured the 426 cubic inch, twin 4-bbl carb configuration that in stock trim posted a quarter mile time of 14.0@102mph and 0-60 in 5.8 seconds. 

By comparison the Ecoboost 4 cylinder Mustang will rip off a 13.7 ET and 0-60 in just 5.1 seconds!

But let's talk GT500. The 2007-09 delivered 500 flywheel horsepower and averages around 425-440 rwhp on a Dynojet dyno on 93 octane.  Add a 123mm open air intake, a larger throttle body, a smaller pulley for 5 more pounds of boost and a Venomous Tuning custom calibration and you can see as much as 90-100 more horses at the tires!

Think about that!  For approximately $1700, you can add 20-23 percent more power in minutes and that's not even close to the edge of what it will tolerate. 

Same goes for the 2010-2012.  Although each of them came with a factory cold air intake and different calibration, the net results per dollar are about the same. 

As for the mighty 5.8L 2013-14 Trinity; same thing.  Stock will average 585-610 at the tires.  Swap the 2.67" factory pulley with a 2.40", a larger throttle body, a larger cold air and Venomous Tuning custom tune and you're looking at 680-700 at the tires, depending on fuel quality.  

So, when you're at the next car show or a weekend Cars & Coffee and see everyone drooling over the nostalgic icons, just step up and enjoy it with them. But know that THESE are the "good old days" of power and performance.