See I'm thinking that for such tiny turbos and low boost, the stock intercooler. Being a decent sized front mount intercooler, is probably sufficient and could even hold up to the flow demands of more boost. But I'm sure the piping can be very much improved.
I also saw that tuners such as
Discovery Automotive use Water/Methanol Injection systems with their BMW's and get great results.
Aquamist
I also found this brand
Devil's Own Injection
Kits from them usually run around $300. But I think I would trust Aquamist more...
These systems yield great power gains, as well as being really good on the motor. Does anyone have any experience with Water/Alcohol Injection?