hi bought an rs then the block cracked anyway in the cars paperwork theres a 500 quid receipt for a stage 4 head with big stainless valves n ported n flowed is there any way to tell on the head as ive fitted a new engine now and was gonna sell it on ebay if it is what it says it is,the valves look big almost to the end of the pot ,just dont wanna sell if its a standard one as how frequent these motors get replaced etc cheers