Please. The 2005-2010 Mustang's V8 was part of the modular engine family. It only had 3 valves per cylinder and 1 camshaft per bank. I still think 300 HP is a massive improvement from the 210 that same 4.6L V8 produced when introduced around 1993, and definitely a step above the 265 HP 2 valve per cylinder SOHC 4.6L that powered Ford Crown Victoria police cars. Meanwhile, at that same time, GM introduced the 300HP 4.6L Cadillac Northstar V8. In 2006, a 4.4L variant of the Northstar produced around 450 horsepower thanks to a roots type supercharger. Don't knock it for using a blower. Jaguar did the same thing.
The Mustang has never been considered fast unless breathed on by Carroll Shelby, and even then it was only ever good in a straight line. The Mustang, to date has always been slower than it's main rival, the Chevrolet Camaro.
And don't knock the Viper either. It doesn't have overhead camshafts (which are more efficient) like the Mustang or Cadillacs. The Viper's V10 was developed in the 1980's and based on an already outdated V8 design because Chrysler was short on cash. To think it's now screwing out 650 HP is absolutely amazing when the original Viper had 400 from the same basic engine. A lot of American V8 engines tend to use the incredibly outdated pushrod engine design. For example, the Chevrolet Corvette (all except the 1990-1995 ZR1), and the Chevrolet Camaro (all except 2010-present V6 models) use pushrod engines.
The CURRENT Mustang's 5.0L V8 makes a much more healthy 420 HP, and 444 HP in the Boss 302 model. The base Mustang's 3.7L V6 makes 305 HP, or the same as the pre-facelift Hyundai Genesis Coupe did from it's 3.8L V6. The current Camaro's V6 makes 323 HP and has been shown to be able to produce more, but was detuned for fuel economy (That V6 is still no slouch).
Don't focus on the larger American engines, because lately, top of the line tech has been showing up more often than not in SMALL American engines before it reaches the bigger engines.
The rev-happy Quad 4, GM's first ever in-house DOHC 4 cylinder made 190 HP from 2.3L (The 190 HP variant was known as the W41 and an upgrade over the normal High output Quad 4). That doesn't sound like much now, but it was one hell of an achievement to do without Vtec when it was released in 1991. To this day, American 4 bangers have yet to top that output naturally aspirated and of similar size. At the time, it's specific output per liter was only bested by Ferrari, Lamborghini, and BMW.
http://www.youtube.com/watch?v=ep9HprLXlUM
This link feature one of the mentioned W41 cars. The power ratings advertised were conservative, and the engine actually produced more than stated.
http://www.youtube.com/watch?v=zye7eMPtHEs
Americans are reluctant to change their V8 engines to overhead cam units. Not because it won't make more power or be more reliable, because it will (not that pushrod engines are unreliable). The problem is the current pushrod engines (excluding Ford) are part of American tradition. Ford took HELL when they stopped making the small block Ford pushrod V8 in favor of the OHC Modular V8, which is now making more power than was ever possible with pushrods.
The problem with pushrod engines is a few things. One: They can't rev very high. The reason is because the pushrods themselves are more susceptible to bending or breaking at high RPM. Most pushrod engines only rev to 6,000 RPM. Exceptions include the 2007-2012 Chevrolet Corvette Z06, whose 7.0L V8 revved to 7,000 rpm, and the other exception are the original Corvette and Camaro ZL1 from 1969 for achieving the same 7000 rpm redline.
The other main problem with pushrod engines is that there is a LOT of power lost through the pushrods themselves. The camshaft in the block pushes the lifters, which pushes the pushrods, which pushes the rockers, with push down on the valve springs, which opens and closes the valves.
Do not bitch and moan about pushrod engines because it's what they're capable of. Bitching about Ford screwing just 300HP from the Mustang's V8 from 2005-2010, I can understand because that's an OHC engine. In general though, most of the low power per liter engines are pushrod engines.
