360 Cat bypass pipes

Pretty sure they all do.......

 

thats precat. OP is talking about main cat, hence the "pipe"

 

yes, its inside of the exhaust manifold, aka header

 

There are few issues with the catalytic converters themselves, but due to heat/performance/price, many will opt to put an aftermarket system in. The problem that you are referring to are the precats in the exhaust manifolds themselves, that affect 2000-2004 360's. To eliminate that possibility you can get a set of aftermarket headers, but you will probably have to deal with a CEL or get the ECU programmed. The headers typically run a few grand, but you will be virtually eliminating an issue that could cause a much more expensive engine rebuild down the road. I believe someone is selling a set in the classifieds right now.

 

or buy challenge car headers. and also eliminate the 2nd air injection, in which case passing smog could be an issue in the US.

 

Good call. I believe you may still need an ECU tune for that.

 

Smog checks aside. Without a tune it would still have a CEL all of the time so you wouldn't know when there is a real issue.

 

That's a complicated question. Generally a tune just turns off the sensor & warnings. A few can alter the sensitivity and/or range of the sensors so they continue to work. Theoretically retuned is better for everyday use; it produces power more uniformly across a wide variety of temp and other conditions.

 

My challenge headers threw a CEL straight away. O2 extenders cured it. 3 years now.

 

No, they do not have precats. BUT don't confuse CS with Challenge. They are different things.