need info quick, ls6 pcm

when switching from an ls1 to an ls6 do you have to reprogram the computer? I always thought you didnt but the shop is telling me that you have to. any quick help is greatly appreciated, cause id like to get this going asap as im without my car right now.

anybody? so far ive read that an ls6 will run fine on a stock comp. and that it will need to be reprogrammed. :confused:

Might need tweaked a little for best performance, but it will probably run as is...

thanks man