well a couple.. does an rb header replace the pre cats on an 82 12a car?

and if i remove the main cat on the same car, cut the flanges off and weld a piece of straight pipe in there, would it be the same as a "race pipe"? I have a spare stock exhaust that i would use the thick walled piping out of to weld in. Im not really being cheap, but if i can make the same thing, or close to, then why not?

 

the header will replace the pre cats and instead of cutting the flange off of the converter, you can buy a new flange from mazdatrix or racing beat and weld in a "test" pipe in place of the converter.

 

make sure the measurements are accurate, i learned that the hard way. i ended up having to butt weld on 3 more inches. just get two flanges and put a pipe or presilencer in there. it is also loud and annoying with a header straight to a stock muffler.

 

I had mine done in a muffler shop with the car up on the lift so we could test fit everything. The guy was nice enough to let me help. I don't know if the 85 setup differs, but my header ends roughly where the main cat would begin. And like BMeyer said, straight header to muffler is quite loud and pingy... I would recommend a presilencer.