What level of ESD are you thinking about? I know 3M's heatshrink is rated for 600v and has a dielectric strength of 500-900v/mil. I'd link to the datasheets, but the name of 3M's document server trips the forum spam filter.
Google "3M heat shrink tubing datasheet" for details.
When you void a product warrany, you give up your right to sue the manufacturer if something goes wrong and accept full responsibility for whatever happens next. And then you truly own the product.