no not driven the car since helix fitted just lost me rag and left it there til master is fitted, spoken to a couple of my mate mechanics and they say it makes sense, first ford tried to tell me the helix wasnt up to the job even though they are good for 400bhp+ then they tried to tell me the new clutch was faulty and today they agreed it could be a master cylinder as it would make sense why its slipping worse as the thicker clutch plate would be engaged more if the slave cylinder is not returning properly due to master cylinder holding pressure, and so it goes on i just hope it sorts it.