I recently purchased a Forge unos MBC for my stock turbo IX. It came with the mounting brackets and the additional (heavy) spring. It doesn't have any vaccum tubes though. I found out how to install it on the forums but after searching threads on MBC, FORGE, and Installation, i didn't find any specific mention of the actual reccommended internal diameter size for the vaccum tubes. So I went to a parts store to ask what was best and they were not sure. They have sizes from 3 to 8 mm (internal diameter) vaccum tubes. So which is the perfect size for this application?

 

4mm is what you want... get it at autozone, checkers, napa, etc. I took my MBC with me when I got tubing to make sure it fit good. Use a little wd40 if you have trouble getting it on the nipples, lol.

 

Thanks!