Where do I buy them? Summit has them for the LS1, are they compatible?

 

I know this is not the answer to your question; but.... I went the SIM route and it was a waste of money. I eventually had them tuned out. This is what I should have done to start with.

 

I agree with matt65, if you want to have a tune then you could ask the programmer to turn them off. If you don't see yourself needing a retune and just want to use the sims, then yes the LS1 sims will work they both have the square connector.