efi conections 24x kit
 

has anyone used it on a lt-1? how the tuning work out and can u use ur stock harness or do u need to get a ls1 harness or a efi connection harness? been thinking of getting rid of my opti

I run the kit with just about all the bells and whistles. Your LT1 harness can be repinned/reworked for cheaper than EFIs harness. I chose to buy their harness and I'm happy I did but others have had good succes redoing theirs.

Since your LT1 PCM is replaced with the LS1 unit, all of the tuning suites out there made to tune the LS PCM will work (HPTuners / EFI Live). EFI does not provide a mail order tune or offer tuning services so you will either need to send it away for a mail order tune or have it dyno tuned.

Most other parts besides their actual engine hardware can be sourced to save a few bucks as well.

I've been very happy with my kit so far.

does efi conection do the repining of the stock harness or do i have to do it myself

You do it and save monies. They provide you with a "guide" but that's about it.