I have had it on my 2005 Roadster for well over a year and it's good. Lightens the load at slow speeds (like when parking or at the petrol station) and seems to disappear at higher speeds. It was installed in my garage, by myself and my friends. Can't rightfully say, but yours may be an installation problem.

Cheers,
Mark

Mark

1934 SS MX4
1938 Series 1 DHC
1951 Plus 4
2005 Roadster