just wondering what the advantages and disadvantages were of running a oil only cooled turbo. I have a 05 sti if that makes a difference. Same with ol and water. anyone know?

 

Oil is prone to coking which can be detrimental to a turbo. Over time they require more maintenance but given the performance application with which you'll be using it, that should be expected. If you take the proper measures such as a turbo timer, doing the scheduled maintenance and perhaps installing an oil cooler you'll make the differences negligable. Don't let the cooling of a turbo determine your choice, there are much greater considerations to worry about (i.e. spool, boost potential, manifold options, supporting mods, etc...)

 

this one is also set up for a external wastegate...is that made for higher boosting cars?

 

Yes, external wastegates hold boost more efficiently than internally wastegated (stock STis, FP Green, etc...) turbos. In my opinion they also sound alot better.