Do lots of research before buying W2 heads to avoid some issues and to make sure you get the set-up you want or need. I bought a set of Econo W2 heads and picked up some Crane and MP W2 rockers. I did some port work and with the stock 2.02 valves they were flowing slightly over 300 cfm. I ported the W2 intake and threw it in my Duster. After cam break-in I started it a few times in the shop and noticed a small puddle of water on the passenger side. Sure enough the heads cracked on the outside lower row of bolts by the W2 cast into the head. I ground the crack out and used Splash-zone epoxy to fix it and headed to the track. My Duster ran high 9 with that combo but about 3 months later the drivers-side head cracked in the same spot and even after a quick repair the crack continued to grow. After some reading I found out that some of these casting were known to have that issue so they are both leaning again my shop wall in the SCRAP zone. I'm just glad I didn't go to the work and expense of installing bigger valves.