The exhaust system is only partially what makes a Raptor sound the way it does. If you look here: MORE POWER COMES STANDARD ON 6.2-LITER V8 ENGINE ON TAP FOR MORE CAPABLE 2011 FORD F-150 SVT RAPTOR | Ford Motor Company Newsroom you will read, " The exhaust for the 6.2-liter engine was uniquely tuned to deliver the performance-oriented, high-horsepower sound customers want. Additionally, a unique firing order gives the 6.2-liter a distinctive roar. The 6.2-liter V8 is similar to the engine used in the all-new 2011 Super Duty, but features unique tuning and a special cam profile to produce more horsepower and torque."
My sense of this is that it is mostly the engine that makes a Raptor sound like a Raptor.
Makes sense.. Good read..thanks