Which manufacturer makes the best cylinder heads for the above mentioned gearbox versions? I've recently bought V6 cylinder heads from Lonex and KA and both had severe production flaws on the nozzle. I'm not talking about slight surface imperfections, they have deep grooves and cuts that causes damage to the air nozzle o-ring and will cause air leakage. So, who makes cylinder heads that are properly made with good quality control? SHS makes cylinder heads, but not for the V6 as far as I know, otherwise I would try an SHS cylinder head.