I have recently installed a set of H&R Springs on my 2015 SHO and am pleased to say, the results are fantastic. Highly recommend.
Impact
I measured from the middle of the center cap to the fender rim.
Before
Front: 15 1/4"
Rear: 15 5/8"
After
Front: 14"
Rear: 14 1/8"
Front drop: 1 1/4"...