The X3 heat resistant stickers are apparently not available any more. You used to be able to get them from here:
http://www.leovince-uitlaten.nl/detail/444968-412131r-hittebestendige-x3-sticker
Reproduction vinyl X3 stickers are readily available on ebay, but obviously they would not work on an exhaust.
You might have to consider changing both sides to this version, which is the only genuine LV heat resistant sticker available?
http://www.leovince-uitlaten.nl/detail/5051293-417705r-leovince-hittebestendige-sticker-417705r