What size is is you're specifically looking for?
Teknic's "Venom" jacket goes up to a size 18 (and actually they run a little large). Great quality jacket, good looking, and comfy (has stretch Kevlar panels in it).
http://www.teknicgear.com/catalog.php?styleid=1&pid=91
Their "Sprint" pant also goes up to an 18:
http://www.teknicgear.com/catalog.php?styleid=1&pid=97
In mesh, the "Supervent" goes to size 18:
http://www.teknicgear.com/catalog.php?styleid=1&pid=95
And in textile, the "Sequioa" goes to a 20:
http://www.teknicgear.com/catalog.php?styleid=1&pid=94
Then there's the G-line from Hein Gericke.... WONDERFUL stuff. Pricey, but well made and great fit.
The Bonzai jacket goes to size 16:
http://www.experience-g.com/product_...products_id/75
As does the pant:
http://www.experience-g.com/product_...products_id/17
Saratoga (another leather) goes to 18:
http://www.experience-g.com/product_...roducts_id/109
La Jolla (leather) to size 18:
http://www.experience-g.com/product_...roducts_id/118
Salinas jacket to size 18:
http://www.experience-g.com/product_...products_id/91
And I'm sure there's plenty more....
Also, the Joe Rocket Trixie comes in an XXL in one of the colors (can't recall which one... I think it's either the all black, or the black/ivory/red) which would fit about a size 18. Some of Power Trip's jackets go to a size XXL as well.