421 North to 22 is a good route but you will not save 30 minutes unless there is some really bad traffic mess on 31. I live just west of town on route 22 and travel to Indy frequently, about the same time either way. Might be a bit quicker if you know the back route to the speedway. However, it is 2 lane road all the way to Kokomo and if there is traffic on a Friday evening it can be hard to pass. So, if you want to avoid the construction, take 421 North but don't expect to save a huge amount of time.