Exhaust Headers Options

[Redline08]

If I put stainless steel 4-1 headers on my 99 celica gt, will it still pass inspection? (emission problem?)

[Bitter]

first of all, stop calling it the primary cat. IT IS NOT! its the warmup cat, the technical term is TWWUC, Three Way Warm Up Catalyst. its primary function is to heat up faster than the main cat and help to eliminate startup emissions until the main cat gets upto operating temperature.

now, if you dont have the sniffer emissions (where the put the probe in your tail pipe) you can use a cheater to get rid of the check engine light so you pass the computer check. you use 2 sparkplug antifoulers in a special way to space the sensor back from the exhaust stream so it gets a smaller sample of gasses and thinks that eveything is fine. you'll want to do that to the sensor that sits below the warmup cat, not the main O2 sensor.

if you DO have the sniffer test you can do 3 things to help ensure a pass
1. use the cheater to get the check engine light to go away so you dont get an automatic fail
2. drive the car around and drive it hard to get the main cat hot, with a good hot main cat you may pass the test.
3. if you dont pass with a good hot stock main cat, get a larger capacity cat welded into place. something intended for a larger V8 should be able to do the trick, and while you're at it you can get it as a highflow cat too!