the b21a1 engine has FRM cylinder walls that require special tools to hone them,though if you bore past this, I guess you can just use normal honing tools since the FRM will be gone.

if you're assuming that you need too have they cylinders bored because you're burning oil, there's a much better chance that your walls are fine and the rings are chewed up.

look at this preludepower.com discussion of the b21a1 engine: http://www.preludepower.com/forums/s...d.php?t=191845