The SVT headers were fabricated and developed by Cosworth and have been proven as the best out there over all of the 3rd party companies.
As for the Mazda3, that's a duratec engine to start with and the SVT is a Zetec engine, so that's where the difference mainly starts.
Hatch Nation Member: #147
R.I.P - FELLOW FF MEMBER, IZZY, BLK2k3GTS, will always be remembered. We will compete on a different course again one day.