We tested several both 2.25" and 2.5" diameters of pipe and found no losses in the low end of the rpm range even with the somewhat large 2.5" pipe size, and a few horsepower increase on the top end. Testing was performed on one of our customers' cars, a 93NA, with an aftermarket intake and nology wires as the only additions to the exhaust systems tested. All exhaust systems were tested with backup runs.
If you have a Home Made Engineering header (made by MR2OC member) select the "No Header" option.
Video of a starup, take off, and drive by with the NATKO (6" mufflers) courtesy of customer Jamie Cissell: Click Here
Made to order.
COULD TAKE UP TO 4-6 WEEKS TO BUILD, (depends on lead time for the mufflers/tips/flex).
NOTE: If you are in Alaska or Hawaii, there may be additional shipping required.