I cannot understand why anyone would risk destroying an engine worth thousands and thousands of dollars by using a set of junk heads to save a few hundred dollars. Worse yet, is paying to have the junk heads "gone over and touched-up". You can polish a turd all you want, but it is still of a piece of sh*t. Learn from others' mistakes, go with quality heads. A top-notch engine shop will refuse to use junk, polished or unpolished. JMHO