OK if I supercharge my 99 Cobra

I don't want to sound like a jerk, but this exact question has been asked at least a dozen times in these forums. A simple search will bring up all sorts of threads on the subject. The bottom like is unless you have a donor 03/04 Cobra you can scavenge all the necessary parts from it's just not worth the hassle attempting to retrofit an Eaton M112 onto the older 4v Cobra's. There are a WHOLE BUNCH of other parts besides the blower itself and most 03/04 owners are only selling their Eaton's when they upgrade to an aftermarket blower. All the supporting hardware is retained when they swap for a KB or Whipple.

It's cheaper and easier to just purchase a complete kit specifically designed and engineered for your application.

U.M.