Add the elbow macaroni, water, and salt to the Instant Pot. Set the Instant Pot to Manual High Pressure for 0 minutes. As soon as the Instant Pot comes to pressure and the pin pops up, do a quick pressure release. If you want to learn how to avoid a big mess when doing a pressure release on pasta, make sure to check out my flip-the-trivet mess-free pasta method.
Once the pressure has been released, open the pot, and carefully mix the pasta around to release the steam and let it to sit for a couple of minutes to allow any excess water to evaporate and absorb into the pasta.
Mix in the ingredients for the dressing - mayonnaise, mustard, sour cream, and pickle juice. Ensure that the pasta is evenly coated.
Add the Spam, pickles, lettuce, peas, and olives to the pasta and mix everything together very well.
Cover and allow to chill in the refrigerator for a few hours before serving.