James: I made custom hardwood arrows (and others) for over 10 years. Never used mahogany but my experience was that if the wood the shafts are made from is properly dried then spine doesn't change even if you change wood species. I used birch, maple, ash, fir and numerous softwoods. Never had issues with spine between wood species and never got a complaint about the spine being off. As long as they are straight grained and properly cured you should have no problems. Check with the supplier. Shafts made from straight grain, quarter sawn logs seemed to be best.