I have the BRC system on mine, fitted at 7000 miles and now at 115,000. if anything the engine gets better with age, Brian once told me that the engine will take about 85,000 miles to run in and he may be correct, when I was in the 90's it seemed to be noticeably smoother than before, and ever in the last couple of days with an additional 20,000 miles on it stills seems to be getting smoother.