im lookin into getting exhaust very soon within the next coming weeks. i need to know everything from the headers to the muffler tips i need. and if run str8 with no cat would it mess up the performance? would getting exhaust mess with the preformance of the car? what should i do for the most and best preformance outta my 85' rx-7 12a 1.1L (completely stock).

Jimbo

 

well, if you got some cash to spend, take a look at www.racingbeat.com or even better www.mazdatrix.com, they carry the same exhaust, but have better custo service and hardly ever are out of stock.
as for your other questions, a header into a straight pipe to a muffler will be noisey, but it will deffinitly add more horsepower then what you had stock. If your going to build up your own system, then take care to make sure you get a good muffler, nothing packed with glass or crap, make sure its all stainless steel. and be sure to put on a couple of presilencers, as it will be noisey

 

is there an O2 sensor on my cat? how do i go about gettin the sensors right with everything?

 

The o2 sensor is on the exhaust manifold (I believe). If you get a header from Mazdatrix it should have the hole for the o2 sensor.

 

There's no O2 sensor in a stock 12a exhaust system.

 

12's are carbed, they have no need for an O2 sensor. The only 1st gen that actually needs an O2 sensor is the Fuel Injected GSL-SE...

 

Sorry for the bad info, I'm used to my 13b. I haven't had a 12a in a long time.