they are 15mm right? i cant get any of them to budge, not one, all i have in 15mm is 3/8" drive and i'll just snap those if i put too much pressure on it, so the only real good way to do it is to get a 1/2" drive 15mm socket?

 

yes, you need a 1/2 drive, on a breaker bar. My impact wouldnt even pull them out. I sat on the engine, had someone else hold the engine while I tugged on the breaker bar.

 

yeha, we used a breaker bar on my buddy's 305, but it was 5/8" , none of this mm crap

 

just get a good long 1/2" breaker bar and a 15mm socket and give her hell. just go a half a turn on each bolt to break them loose in the opposite of the tightening sequence. it is possible to warp the head otherwise. its not likely but it can be done if this doesnt happen. once you get a half a turn on each bolt, then you can take them out.