CX300s; Is there a bigger silicone ear tip than the biggest ones they come with?

[mcdj]

I recently purchased the Ultimate Ears Super.fi 4vi for the iPhone. I wasn't a fan of the thin bass (but they sounded nice otherwise). One of the things that made it hard to let them go was the XXL silicone ear tips, bigger than any large tips I've used (EX71, CX300, etc.). The resulting seal was almost soundproof. I would have kept the 4vi tips but they didn't fit my CX300s. Has anyone seen an XXL replacement tip that fits the CX300?