Hi Darryl, yes I have heard Peter Tan in HK does the mod for rather quite cheap. The replacement filter Baader UV/IR can be purchased from ALpine Astro for $88 US:
http://www.alpineastro.com/filters/uv_ir_cut_specs.htm
im not sure about the same thickness with the 450d , but the 400d and the 40d is the same.