thanks Anthony, probably a good summing up of how my car is will look at balacing the tbs this week and if i have no success then will have a visit to T&R got just over 9000 miles and had a refresh and a rebuild (scholar 1900 ) , it does drive so well with an open road in front so i think it is just a little off at tick over and lower revs . had a real good go at sealing the exhaust and has improved a lot since doing this, still loving owning and driving the car after 8 years since my previous caterham