Hi everyone newbie here,

I have a 325i (E30) which is currently in a mild state of tune, problem is the big / main end bearings are starting to show signs of wear. So I'm planning a re-build in the near future. What I would like to know is, How much can the cylinders be bored out to?. Also, how much can the throttle body be bored out by?.
What sort of gains can be expected by a large bore throttle body?

All help apprieciated