This is how i made my installation w/o a boot. But you'll need a tig welder...
Edit: Hm attach photo didn't work..
Thanks, as I don't have TIG I'll do like that to the next TB, I have three of them:D but I'm out of home for a week and can't measure
For now I want to know what size of silicon reducer will fit

(sure with TIG would be the best)
as for the oil pan you will see step up's to where the oil pan gasket is and on the last step up is where I did a tap.. I should mention you get one chance at the tap and it has to be perfect or you will find yourself geting a bung welded
I'll do higher I can

sure, it's not the first pan that I tapped, it's only that I don't know where is the oil level inside the pan and how is the interior of the pan
