2004 GTO (OS 12587604) COS options

[Kevin Doe]

I have an LS1/T56 with the wiring harness and computer from a 2004 GTO in my car. I pulled the stock tune, and the current OS is 12587604. Looking through as much information as I could, I decided that I would like to use COS#5. But now that I'm looking more into COS#5, it looks like there isn't a 1MB COS#5 out there.

From the chart, it appears as if I need to use a COS with the numbers 041100XX. A speed density tune is an absolute must, as I have a dual 3.5" intake, so no MAF sensor.

If COS#5 is not available, what is my best alternative? Is there a COS#3 that I could use given the current OS in my GTO PCM? If COS#3 is availabe, would I be able to upgrade to COS#5 if/when it becomes available?

Thanks,
Kevin

[wait4me]

Yes just use the cos 3. so the part number would be 04110003.

IF the os 5 becomes available, you would be able to easiely upgrade.

[Kevin Doe]

Thanks!!!!!

My next question is this, and I think its a fairly stupid question.

Where do I get the 04110003 file? I've looked all over these forums, on efi lives main site, searched here, I just cant' find anything. I'm sure the answer is painfully obvious though.

[dc_justin]

That COS file was installed on your computer with the software installation. To find it, go to my documents/EFILive/V7/Bins/Custom OS

Should be right there. You'll want to load the file with the "c" at the end of the filename.

Justin

[Kevin Doe]

Ok, thanks, I knew it would be stupidly simple. I'll do some addional reseach, but what does the "c" mean at the end of the file?

[Chevy366]

The "c" was for a corrected file that caused lean start ups , but if you have current software no need for the "c" the files have been corrected .
Nice job on the install .