I am currently saving for a heads/cam package. I have found the two companies that I want to use. Neither of them offer full details on their heads, they use vague terms like "competition valve seats" and such. Which would you choose if you were to do this mod? Also, I was wanting to get them assembled with either comp cams XE274s or 278s. Are the 278s not streetable? Will they pass emissions? I am registered Illinois