K20 is the way to go IMO. I had a BONE STOCK K series head sitting on the table next to my FULLY race prepped 2G DSM race head (and I mean built to holy hell and back). The DSM head was making me 700+hp on my car. Anyway, the stock valves in the K series head were significantly larger than the OVERSIZED valves that I had in my race head for my DSM. The K series head will flow well over 300cfm in stock form, no porting, etc. You have to fight tooth and nail, and port it within an inch of its life, to get the Mistubishi head to do that. K series motors truly are top notch. That's what I would build if I was gonna build another 4cyl. However, I've moved on and have a 2JZ now, so I could care less about the 4 bangers anymore!