Also sounds like BS to me. The "big hole" in the transmission I assume is the round hole in the bellhousing? If this is so it is either a leak from the Mazda gearbox, unlikely as that is about the only bit of the M3W that doesn't seem to cause any problems, or from the S&S engine? I would go with a leak from the S&S engine side of things. You could have a sniff of the oil to confirm this but you will need to be aware of the smell of engine oil compared to the smell of transmission oil. They are quite distinct. The only other possible source is from the hydraulic clutch release and that will mean that the master cylinder reservoir level will be dropping noticeably.
