I am planning on a 74mm TB, which could probably get by with the stock. My car is doing 195RWHP now and I just added the K&N fitlers, so it should be close to 200RWHP now. If I add any refinement to the exhaust, I will need more fuel. It's not just for today, I saw what looked like a good buy on the injectors and thought I would buy them while I could get a good price.