It depends. If you scored between a 220-230 on Step 1, and you score >230 Step 2 (better yet >240), it can definitely help you. Make sure not to release the scores, though, so that if you do worse it isn't sent to the schools.
You should be able to match with 220-230, but apply broadly. In addition to improved Step 2, other things that will help you are strong letters of rec, good 3rd year grades, publications, etc... If these are good, and the weakest part of your application is Step 1, then you should be in good shape. Research isn't required, and is a lot of work (one year) for not much benefit, but it could help.