does anyone know if the 97 V6 exaust from the cat-back is the same and the 4 cyl. i know from the down pipe up is completely different but i was wondering from the downpipe and back.

 

Check online auto parts sites such as Rockauto and compare part numbers between engine types.

 

i was just wondering if they are close in dimension. and if anyone knows how to diagnose my car. i know it is running really rich by me MPG and by my exhaust fumes but i cant pin point a problem. my engine still runs fine.

 

Is the Check Engine Light on?

Have you checked the air filter, plugs, etc?

The 4 and 6 cylinder exhaust sysems have differant parts number thus assume are not the same.

 

no, but i do have a header on and that got rid of the cat. i dont know if that is ther reason because i was getting pretty bad MPG before the header and it hasn't changed. but i dont see why i wouldn't have my check engine light on because if the post-cat O2 sensor. i did a tune up about 1000 miles ago, air filter is still good.

 

What is the MPG?

Sluggish O2 sensors can cause a drop in MPG. Sometimes the placement of the sensor on a header can cause problems.

How is the PCV valve?

 

pcv is good. right now it is about 15mpg. ya i know. it sucks for a 4cyl. but i dont understand how it could be running so rich but no miss-fire or any performance problems. the new placement on the header is just a tad bit higher than stock

 

Typically running lean or ign problems cause misfire.

How is the throttle body, clean? Spark plugs and wires OK?

Sluggish 02 sensors can cause reduced MPG.

If haven't done so, do a tune up.

Suggest you pickup a Haynes shop manual that contains info on testing the various sensors and other devices.