hi everybody, just got a few questions about a b20 head. im in the process of building a b20 to go in my 544. when i got it home and tore it down i found that it had a b18 head on it so i searched ebay and found a b20 fi head and it just arrived. my first question is about the little rings that go between the head and intake , my b18 head is machined to except them but the b20 isn't, are they really necessary? and i have read that you can use freeze plugs to cover the injector holes but there dosen't seem to be enough depth to hold a plug, do you have to machine them a little deeper or what? and last, about the little oval cover on the right of the thermostat, it dosen't look like the one from the b18 will work on the b20, are they available? any help on these matters will be apprciated. thanks mike