I'm in the process of designing a front mount twin turbo system, I have never built such a system before so I've probably got some pretty stupid questions here
- Waste gate dump back into exhaust or to atmosphere?
- Air to water or Air to Air what cools better?
- I'm thinking about using a ball bearing Turbo any body having any problems?
- Whats the schedule of material for exhaust side? and air side?
- where on the Engine do you tie in the oil lines?

 

- Waste gate dump back into exhaust or to atmosphere?
More flow, easier to build when vented to atmosphere. Noisier though.

- Air to water or Air to Air what cools better?
Both can be efficient. Nice thing about the air water though is you have a whole resevoir of cold water to heat up and it cools off when your not boosting. But if the pump fails you loose your intercooler and could damage your engine.

- Whats the schedule of material for exhaust side? and air side?
stainless for exhaust and aluminum for the intake is probably the nicest. Steel is cheap, readily available and easy to work with, i used it for both sides, you have to deal with rust later on though.

- where on the Engine do you tie in the oil lines?
there is a blind hole you can drill and tap right above the oil filter