I would replace the passenger side exhaust header and everything behind it with with high flow exhaust pipes and muffler including CAT. This will relive alot of back pressure. This will help alot at low cost. I will warn you up front- Larger turbos require the right upgrade with respect to injectors,fuel pump, hot wire kit, adj fuel pressure regulator. If not, you may get knock and blow the engine up. Also, don't buy an adjustable waste gate actuator unless you are an experencied mechanic on this type of car. I made the mistake and it cost me the price of a new motor after only 8,000 miles on the other new motor. Good luck brad