SFB Mounting Advice!!!!

I have a pair of SFB's mounted at -5 from true center. They were my all mountian ski and generally just used them everyday. However, iv started park skiing and don't want to buy a new pair of skis for park because i love the flex and feel of SFB's so am considering mounting them up at true center. Is this a good idea? I am 5'9", about 160. They will really only be used for park and jibbing around the mountain-i can steal my dad's Mantra's for everything else. So really; given my size, is it a decent idea to mount true for a big park ski? I imagine that it should make them more manouverable since the tips are effectively shortened but need some input... Cheers