3" is as tall as I have found so far, but there are some coil overs coming out now. Dual turbos? You'll be the pioneer on these, but that would involve a LOT of engineering to do, just finding low compression pistons would be a challenge, not to mention headers and a reprogramed ECU and injectors.
Among other things, the transmission and rear differential aren't going to hold up to much more than stock power levels. This will be the hardest part of any reliable power upgrade. For the lift, join the Facebook group Ridgeline Offroaders. You will find much more info on the subject.
I think if you go higher than 3 inches the biggest challenge will be the suspenssion lower arms on the front end are going to be short, not to mention the strange angle the spindle will end up, the rear might have problems also with the lower arm length.
As for the dual turbo, there is a Class 7 truck racing the SCORE offroad championship and i believe they are running dual turbos with the Ridgeline engine, you can check Jeff Proctor FB page.