So I bought my warrior in Nov 2013. 50 hours later I decided to upgrade it to 160HP so we would also get to see general health of the engine inside. While glass beating cleaning if first cylinder we noticed a crack between the plug and port area if header. We pulled other cylinders and found that 3/4 have developed cracks which are not through the surface yet and 4th one had hairline crack. Compressions last month were low 70s. After research and cost factor I decided to go with millennium instead of lycoming as they were 850 a piece instead of 1080. Decided to use the diff money to install edm700 as well. So I am wondering if you have any suggestions on how to breakin new cylinders and what should I be looking out for? I am sure I didn't shock cool or overheat those in past but probably had been there for a while and it seems at overhaul 14 years ago, they might have used the reman ones to replace. My plane is ttaf 3000 smoh 1000 
