I am going to try to bore out the IM myself to match my TB. Okay I know .. Good Luck! ( I live in Europe and to ship a bored IM would cost a lot to my country.)

My question is this. On the engine, I know that it must be bored to match the gasket. But how much deep must I bore the runners?

 

I wouldn't try the runners your self, try and find a local shop. Trust me the runners are HARD to do. You only need to take about 2mm off each runner

 

Brendan,

But how deep up each runners must I go?

Thanks for your help.