So...you never said where you got them from. Any info on your extensions?
Also, if your extending the wire length your adding resistence no matter if you plug ina manufacturedextension or splice in longer wires. Not sure i'm buying the part where your not able to splice them.

 

sorry, lost this thread awhile ago lol....i got the extensions from i dont remember where lol...i think i got em from moesperformance.com ........the ones i have are made by Casper Electronics and the part number for the 24" extensions is 109210

 

If it's the rear O2 sensors (the ones that are after the cats) are giving the code, the PCM should not be going into low performance mode. A rear O2 error, should only give you a CEL and nothing else. I know a guy with an '05 and no cats, has had the CEL for a year and a half, and posts great times at the track.
It's the front O2's that a failure will put you in "limp" mode. Use your SC to make sure you don't havea front O2 failure as well.
You can get rid of the rear O2 CEL by doing the old "Plug Fouler" trick, a one hour and under $10 solution. Zillions of posts on how to install them, here's one:

http://forums.evolutionm.net/showthread.php?t=114931

 

I know this is an old thread but i
have headers and no cats on my truck, my rear o2 senors are not plumbed into anything, just zip tied up, is there anything I can do to them?