The PO of my car already cut the dash. I bought new parts so if I decide to go back to stock, I can. That way I get the best of both worlds. I recommend the front speaker brackets. I put in some 3.5 Infinity Kappa in mine and 6 X 9 Infinity Kappa in the rear. The sound is phenomenal. I was going to add a huge amp, but with my Alpine head unit, it is way loud and sounds great. Have to rethink the amp!