Does your test pipe trigger a CEL?

[snakebit]

If not, how do you avoid a CEL from the rear O2 sensor not reading differently from the front? Are you doing something like this: http://www.s2ki.com/forums/index.php?showtopic=229959&st=0? Methinks my 50k cat that I almost killed with a bad coil pack may be choking my boost a bit.:ack2:

[Wayne-n-Fla]

1. Removing the cat will make your car a lot LOUDER

[snakebit]

1. Removing the cat will make your car a lot LOUDERRight, probably better to go with a hi-flow cat from FM. Who knows when emissions testing will return as well.

[snakebit]

Woops, FM doesn't make one for NBs. Any recommendations?
I could just punch mine out and deal with emissions as needed . . .:shifty:

[Mx5-4me]

the NB CAT is build into the midpipe..

http://www.flyinmiata.com/index.php?deptid=4503&parentid=0&stocknumber=06-58100

http://www.good-win-racing.com/Mazda-Performance-Part/11-1001b.html

those are the two that i know of that are aftermarket. from what i'm hearing the stock one is good enough for a coldside so you could just get a stock replacment.

[Kyp J]

I have the one from Goodwin. With a RoadsterSport muffler (no Roman numerals) it is pretty loud. With the stock muffler it is quieter and sounds really good. I go back and forth. Sounding faster is for autocross and quiet for the highway which is rare.

The only problem is it is too close to the rear suspension and bangs sometimes. At least I think it is what is banging.

[Steve]

If not, how do you avoid a CEL from the rear O2 sensor not reading differently from the front? Are you doing something like this: http://www.s2ki.com/forums/index.php?showtopic=229959&st=0? Methinks my 50k cat that I almost killed with a bad coil pack may be choking my boost a bit.:ack2:

The way these work is by getting the sub-O2 sensor out of the main gas flow so it sits in a little "pool" of stagnant gas. Without going into the whole theory of catalyst monitoring, the idea is to keep the rear sensor from seeing the same "dithering" change patterns in A/F ratio that the front sensor sees. On some systems, people have had success with just hanging the sensor up under the car in free air. Now, none of this is smog legal so the usual disclaimers apply, only legal for off-highway vehilces, yada yada... ;)

[snakebit]

the NB CAT is build into the midpipe..

http://www.flyinmiata.com/index.php?deptid=4503&parentid=0&stocknumber=06-58100

http://www.good-win-racing.com/Mazda-Performance-Part/11-1001b.html

those are the two that i know of that are aftermarket. from what i'm hearing the stock one is good enough for a coldside so you could just get a stock replacment.Those SS pipes sure are purty!

[GO MAN GO]

Woops, FM doesn't make one for NBs. Any recommendations?
I could just punch mine out and deal with emissions as needed . . .:shifty:

Man, Don't do that. I tried that, and the exhaust bouncing around in there
made it sound down right embarrassing. Loud and terrible.

[snakebit]

Man, Don't do that. I tried that, and the exhaust bouncing around in there
made it sound down right embarrassing. Loud and terrible.Good to know. Miatas seem sensitive to exhaust mods and prone to resonances. When I punched out the clogged cat on my CRX, I got a slight bit more noise and much improved throttle response.
Are you happy with the FM 2.5 midpipe? FM warns that it may be too loud for any but turboed cars.

[GO MAN GO]

This is really a "to each, his own" kinda thing, but yes I like it.
It's really not to loud till ya get on it.

For the record, the punched out cat was on the 2.5 mid pipe
which I'm sure didn't help matters. Stock exhaust might not
be so bad. eliminating cat with a straight pipe might also not
be so bad. I think it's just the empty cat (echo chamber) that
sounded so terrible.