I didn't 100% verify your shown parts.. but your on track. Elbow is fine, you can "clear it's throat" so to say (baffle removal) or leave alone. Throttle body and gasket is all that you "need" unless you want the max performance you can get from the upgrade. The ECU will compensate fine for the upgrade. The tune is just getting more performance out of the car.

We've had some college students here that spending $150 bucks extra just doesn't fit in the books and ramen noodles budget, I know those kind of budgets from the past so helping out with a part I'll never use short of testing - trouble shooting isn't a second thought, but going the upgrade route is your best bet..