I brought my S60R to a shop to replace my slave cylinder. He informed me that i should also replace the clutch and flyweel at this time. I replaced with stock clutch and a used dual mass flywheel. Clutch slips at 4000 rpm at half throttle. Shop did job twice and cant figure out why its slipping. It was the original clutch with about 100000 miles on it with no slipping. I bought the car used with upgraded parts IPD software, 3 inch exhaust besides that im not sure. Mechanic told me that original clutch wasnt slipping because the bellhousing had brake fluid in it. What should we do?