I've read a lot of threads on ways to quiet clutch/gear noise. Realizing that there is barely 1/8" clearance between clutch and inside top of the clutch cover I decided to make a 1/8" spacer. A machinist friend of mine made me a rough one out of 1/8" aluminum and now I have enough clearance to put two 1/16" layers of cork (using contact cement). Did it help - yes. Would I go to the expense of paying a machinist to make it - no. Using this requires slightly longer bolts. An alternative to this method is to buy a new clutch over and cut the top off to form what ever depth spacer you want.