The February 2004 issue of 5.0 Mustangs had an excellant article on bolt ons for the 99+ V-6. The rear wheel dyno numbers were as follows. Stock 154.3 hp. Cold air 162.6 hp. 70mm throttle body 157.9 ( it lost power). Pulley 168.3. Headers 165.8 ( it lost power over the factory headers). Magnaflow cat back 170.4hp. Go to their web site and order a back issue.