able to "carve out" your existing housings to take the CHRAs from the GT28RS'. All (exact externally sized) housings have a different internal dimension to accomodate a different wheel size or trim. The wheels are different sizes so the housings have to be cut to the tolerances dictated by the wheel dimensions. I'm assuming the GT28RS wheels are larger, if not the housings can't be adapted to fit a smaller wheel. You may want to give a Garrett distrubuter (ATP Turbo in NorCal) a call and see if they can put a CHRA together for you that will be able to fit in your existing housings with just a carve. There are a multitude of wheels available that are pretty close in dimension and performance. Hope that makes sense, Mark