what is an what model is an s2ki?

 

If you have checked for boost leaks at the top of the engine. Next I would check for blown off/seperated I/C pipeing(when i turn my boost up over 11 psi every once in a while it will blow my pipes off/apart). Or you could have a hole in one of your couplers. A loose wastegate or loose turbo or manifold could do it also. Other than that the only thing left is a blown turbo.