well, techincally, a doch head will bold on, u just need to get a timing chain, this will raise compression (HP), then you could do cams, or u could just buy a bigger sohc cam and do as justtruckin' said, add a cold air. P.S. i have a head, cams, and chain find my post in "nissan parts for sale" but if u wanted to do basic on the sohc PDM-racing.com has a cam for the ka24e motor that would bolt on. its all in how much u want to spend, how much HP u want, and how deep into the motor u want to get. lmk if u want to talk about the top end parts i have