Macs are very cost effective. I have a Mac exhaust setup on my car and love it. Longtubes,Prochamber and Catback exhaust. 5 years no problems. Just keep your undercarriage clean and you should be fine.
Thats a WHOLE lot of miles on your motor too start putting a S/C on it. IMO. Give Joe a call at MUSTANG MAGIC and ask for his advice.
http://www.mustangmagic.com
Ive never found a scratch remover that actually worked for me. I follow the directions but it never seems to work. Maybe my car being Black has something too do with it? Maybe its just me??LOL