ASK THEM WHAT THEY WILL DO IF BY CHANCE YOU HAVE TO WAIT OVER 90 DAYS BEFORE INSTALLING THE HEAD , AND THEN ONE OR TWO OF THEIR VLVS DROP A HEAD INTO ONE OF THE PISTONS , I CAN TELL YOU EXACTLY WHAT THEY WILL TELL YOU AND SO CAN ONE OF THE OTHER GUYS ON THIS SITE BY THE NAME OF CURTIS JOHNSON, IF HE PICKS UP ON THIS HE CAN SHOW YOU PIX OF WHAT THEIR VLVS CAN DO TO A CYL , JERRY