You can have cylinder head work done, too. There are different header designs that would try to minimize reversion, but with a lot of duration and overlap will have an EGR like effect in higher rpm.

 

is an o2 dump at the top of the downpipe?? right underneath the headers??

 

basicly its an aftermarket o2 housing?? just bigger?

 

HKS 272 is perfect, I have them on my car, it will not hurt the lowend, spool up is just like stock, look at AMS cams comparison it spool up just like stock

 

Maybe a quick spooling aftermarket turbo like the BBK Lite, or a Forced Performance White. GSC S1 cams(If they have them for IX´s), as mentioned before an aftermarket lower intercooler pipe, very light aftermarket wheels. If you want quicker turbo spoolup cheaply, then increase the wastegate preload to about 18 PSI, get a flash.

 

I would invite you to first off look at your current tune.