i have a 95 xjr with 109k on it which is the most wonderful car. whenever it is on boost it makes a noise just like the horn is going off. i tell passengers its a special jag feature that lets people in front know i'm coming through. 9 out of 10 believe me but i want to go to a track day soon so i would like to cure it before then. any ideas? common things to check for?...thx