hi
I know they are a double over head cam and the bf -fg's have variable cam timing the heads apparently flow extremely well because their "cnc ported from the factory"?? i know a fella with the bf version and with new plenum, intercooler, intercooler piping , relocated filter, exhaust , fuel pump, injectors and tune his car does constant low 11 sec 1/4 mile passes in a 2000kg body