Reason I ask is to fix my fuck up I made lol, the o-ring Grove on the flange had a small crack and the face was generally pitted ect so me in my wisdom decided to grip it in the mill at work and machine the flange to remove the groove and clean it up ect.....didn’t realise till I got home that there is a small lip that needs to be a certain thickness for the trumpet section to locate into, now it’s too shallow and the trumpet section bottoms out before closing the gap. So I figured a spacer would fix this, not bother about performance gains.