Whats available besides OEM? Is there something affordable whithout machining for fire rings? Or are the Ford ones sufficient w/ ARP studs? If I'm replacing them anyway, is there somthing better to use while I'm in there. I'm towing, sometimes heavy (30 to 35,000 GCVW) w/ an '04 550 w/strait exhaust,Airaid,Banks IC,MSD propane,Snow Boost cooler,Edge Platinum A2,BD converter,lots of guages.....