i have ran my 548 blown big block chevy iron head soild 720 lift roller cam with 240 psi on the seat and 680 open and have not had a problem and this has seen7000+rpm s may times in the last five years and have built may with out on iron heads with no stud girdle but there are may out there if you think you need some. i do not think. so but here they are . crane .jomar. brodix. reher morrison.howards and there are may more