Anyone that is a handle master head will not have isolators in there because they flex and cushion actually changing spring rates instantaneously.
On a street car they can be nice but if you choose the right spring and shock/strut valving you wont have any issues without isolators.
The rear rubber tube inside of the rear springs, if left out, can cause a clang when going over speed bumps if you drive like a mad man over them.
97 cobra