As I said earlier, you'll lose power as I experienced when mine broke, but also, it'll run lean. It will probably be fine running for a few days, but not more. I recently had a leak, many many many times smaller than what you're proposing and the AFR on was off the scale. Usually it'll run around 14-15, but the right bank wasn't even measurable by the gauges, it was that high. I removed the Y pipe and replaced the gaskets and added sealant which has 90% fixed the issue and brought the AFR back to a decent reading, but still not perfect. I can only imagine what it was before on my old Zed with the blow out.