The Tomei Expreme TI titanium straight pipe for the 2015+ Subaru WRX was designed by Tomei in order to reduce exhaust restriction via a completely un-catted straight pipe. By using a 2.38 to 3.15 inch piping layout and making it as straight as possible, Tomei ensures easy power and torque gains.
Unlike stainless steel systems that promise weight reduction, this test pipe will actually shed 9.48lbs (4.30 kg) off. On top of that, since the test pipe is unrestricted you can expect better response without that restricted feel.