Test Pipes / Catalytic Convertors
by Dave Brode
The picture above is a 2.5" CatCo catalytic converter with welded flanges made by Dave Brode to specifically fit miatas (both 1.6L and 1.8L applications). I supplied him with the cat and he welded on the proper flanges in the correct orientation. This can be a cost effective alternative to increasing power from stock while still utilizing a catalytic converter in the exhaust system. The picture above is an example of Dave's work. When I first received the cat from Dave, I couldn't believe how smooth the weld surfaces were inside. The angles of the flanges are matched perfectly to the rest of the exhaust system, and the quality of the welding work between the flanged and pipe is top notch. Without a doubt, Dave's work is incredible and I certainly recommend his services.
As an alternative to a catalytic converter, Dave can also weld the same flanges to a straight pipe commonly known as a "Test Pipe". The picture above is a 2.5" I.D. test pipe. The purpose of this pipe is to replace the catalytic converter, thus reducing restriction in the exhaust tract. The pipe is made of aluminized steel with the same flanges used for his cats.
I tried this test pipe for several months. Performance increases were very noticeable, especially on the high end under turbo boost. The tone of the exhaust also improved! It was just a little bit louder, but the sound had much more "growl" for lack of a better word. Returning to the stock catalytic converter was no fun but driving a vehicle on public roads without a cat is "not allowed" (however, sometimes it's back on). For off-road applications, I HIGHLY recommend this test pipe from Dave Brode. Dave can make them in 2.25" and 2.5" diameters for the miata.
For more information, contact Dave by clicking here.