Dynatech Exhaust - 07-11 Mustang Shelby GT500 5.4L 4V Dynatech Long Tube Headers 1 7/8" Dynatech 1 7/8" Longtube Headers for the 07-11 Shelby GT500. Set of headers only, mid pipes sold seperately. •May be configured with Dynatech 2.5" X-pipe or 3" X-pipe •2.5" is bolt on and connects to stock 2.5" catback •3" requires reducer cones or an aftermarket 3" catback, catback must be shortened More options: •You may buy 3" collectors if you wish to build your own mid-pipe •You may buy 2.5" collectors or 2.5" PowerCat converters if you wish to connect the LTs with the stock X-pipe (or H-pipe on KRs). For 2011+ Shelby GT500 with factory H-pipe and 2.75" exhaust: •You may buy 2.75" collector adapters and connect to your stock H-pipe (requires cutting). •You may buy 2.75" PowerCat converters and connect to your stock H-pipe (requires cutting). We run these same headers on our own 2007 TVS Supercharged GT500 that makes over 750RWHP. The best header at a great price. Fully welded collector, no leaks. Stainless tube and flange design will not rust and does not require coating. Includes all required gaskets and bolts. Don't mess around with shorties. LTs produce 15-20RWHP and 15-20RWTQ gain on mild stock blower cars. 30-40RWHP and 20-30RWTQ gain on upgraded blower cars (TVS, KB, Whipple, at 18psi). We run these same headers on our own 2007 TVS Supercharged GT500 that makes over 750RWHP. We installed these headers and saw a huge gain from 3000RPM on up, even though we already had shorties and high flow cats (which were 20-30RWHP over stock