What can be done that won't jeopardize an extended warranty? If it has been covered, I would appreciate a link. I'm not on here as much as I should be so I likely missed the thread.
If warranty is a concern, I'd consider passing on a full ECU tune. Of course, tunes can be "uninstalled" however, they can still be detected if someone goes looking for it.
Another option would the Burger JB4 system which is a piggyback setup that adjusts boost, fueling, and timing without actually modifying the OEM ECU calibration.
Other than that unit, your basic bolt-ons are a good option. SPD Turbo Adapters are pretty much identical to the OEM turbo adapters are folks are quite happy with them.
An intercooler upgrade is another good option, however, that is more detectable than your other options.
Happy to go over options with you that fit your needs and your budget.
Let us know if we can help!
-Nick