StreetUnit SUS 304 Stainless Steel Test Pipe (Catless)
Application: MAZDASPEED 6
Part Number: SUMS6SSTP
(Off road use only)

The StreetUnit Catless Test Pipe replaces the second catalytic converter on your MAZDASPEED 6. It is constructed using 2.5" SUS 304 Stainless Steel Tubing and CNC machined flanges. The SU Test Pipe is designed to be a straight tube without any bends allowing for the straightest exhaust flow. The SU Test Pipe removes the severe air flow restriction that the stock cat inhibits onto the MS6 exhaust system (photo below). Removing this restriction will greatly improve the performance and power for your MS6.

The SU Test Pipe is a direct bolt on replacement for the second catalytic converter. For flexibility, it reuses the stock donut flange system to allow for necessary movement. The SU Test Pipe includes all necessary mounting hardware and instructions to make this installation a breeze. The removal of the 2nd cat will NOT trigger any check engine lights. The test pipe will bolt right up to both the stock and aftermarket catback exhaust systems.

Why did we use 2.5" tubing?  The stock downpipe tapers from 3" down to 2.4" where it meets the Test Pipe. The 2.4" stock pipe mates inside the 2.5" Test Pipe at the beginning. The volumetric flow rate of the exhaust gas at the exit of the stock down pipe will be kept more constant using the 2.5" diameter tubing. Using 3" tubing rapidly creates unnecessary turbulence in the exhaust flow when changing from stock downpipe 2.4" to 3" back down to 2.4-2.79" diameter of the pipe/flange of the catback.

3.0" Tubing Option: We recommend using the 3" option when using a 3" aftermarket "shorty" downpipe.

Test pipe is perfect for the MS6 owner that...

...Does not want the hassle of installing an aftermarket downpipe
...Does not like the prices of aftermarket downpipes
...Wants to avoid Check Engine Light issues with aftermarket downpipes
...Wants cost efficient HP gains
...Wants an easy, bolt-on install
...Wants sound kept to a minimum
...Wants the ability to easily swap it out for "dealership" visits

Photo of the Restriction Inside the Stock Cat Pipe