had my downpipe replaced on friday and ever since then iv noticed my engine has started ticking slightly and now and again i get a russling noise. the ticking im not to concerned about as its not that loud and i only noticed it with the bonnet up when i was trying to locate this russling noise. basically it only happens now and again not sure of anything related for it to start. but i can have it in neutral and will here it slightly then if i go into first and bring the clutch up to biting point it gets louder/faster. i can also here it when im driving along, mainly at slow speeds. any help would be much appreciated thanks.