I would take it back to the shop that did the repair work and have them look at it again. Most likely, they missed something. They should be able to fix it and send in the repair fee to your insurance company as an addendum. As for the STi cap, you don't really need it and in some cases, it can be detrimental as it can hold a lot more pressure than the stock cap. Unless you're running mods to justify using it, I would switch back to the stock cap.