TaTommyWS6

I just received my mac headers with ORP. I plan on welding in a pair of carsound cats into the ORP. I noticed that the ORP already gas bungs for all 4 O2 sensors!

What would happen if I used no cats, and hooked up all the O2 sensors in the stock configuration. Would I throw codes because the rear sensors' readings would show the cats (which are missing) are not working properly?

Just wondering....
It seems like if you buy an ORP, MAC might as well eliminate the rear O2 bungs since you will probably be running SIMS anyway... or do the SIMS connect "between" the sensor and the PCM, so the holes are still needed?

Thanks!

Tommy <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

1/4master

the simms go where the rear o2's go. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

2000WhiteZ28

You'd be surprised. I plugged all four of my O2's into my custom exhaust with no cats. They were about a foot apart. Didn't throw a code for a month. Then, I got the O2 simms. <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

You can leave the rear O2's to plug the hole when you get the simms, or just get a little bung hole plug to screw in there. You remove the O2 wiring harness, and snap the simms in place.

J&JsTA

I just bought plugs at the GM parts counter for the pipes and plugged the simms into the rear O2 harness. I prefer to have them come on the ORP for later weld in of cats and then there is no need to play around with the bungs later, it's easy enough to plug them up. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />