Well i'm just getting into the honda world and found this cool place thanks too google =) i have a 91 crx dx and i dropped a d16a6 in it did all the mpfi stuff myself i know its done right and have had no problems in the 15k miles i have put on it.. now for some questions i just bought a z6 head so i think the valve cover doesnt say vtec just a honda sign in the middle of it the spark plugs are moved to the front and the vtec solenoid is there so prolly no big deal .. but i replaced my thermostat and now code 21 comes up Spool Solenoid Valve checked all the wires everything looks good no clue what to do and also what ecu do i need to change over with the z6 head and what mods and stuff do i need to buy for good performance any help would be great and considering u just read one giant run on sentence thanks!!!