Really thats news to me? What ****ty brand were you using or was this something you heard?
My previous GTP had a manual summit racing one for 3 years before I sold the car. Never once had a leak when the gasket and cover were installed.
odd I never had clearance issues with my previous GTP then again it wasn't lowered. Just installed a manual on my current GP that has eibach springs. It sits fairly low and clearances just barely.