is it worthit to upgrade my supra with stock turbo?

[Grandavi]

Metal Headgasket = Shaved head if I understand it correctly. And you will want to have the block lapped as well. (of course.. I have not done this, nor am I a mechanic.. I am going off of my personal understanding from reading) Going metal headgasket is (from my understanding) the worst way to go if you do it wrong. I would research that prior pretty strongly... I wouldn't trust a shop unless I understood that myself.

After that, I have heard of people running 16-18 lbs boost, but again.. having never done it.. I dont know if I am right. Remember, its not only the headgasket when you start going in this direction. Really, though, unless your going to run it on a track (racing it) I dont see the need. Running a car with over 450 HP on the street is kinda insane.. lol. Would love to, but I drive fast and afterwards always think.. "man.. am I glad I didnt get caught doing that". At my age it would be embarassing.. lol. (not to mention very expensive if not criminal)

I dont know about the highways where you are, but 150 kph (think thats about 90 MPH) is very common on the runs between the 2 major cities here so I want to be able to do that without stressing the car too much. Its at 180 KPH and higher that I start to really worry... (although I think my 88 MKIII currently tops out at about 185 KPH)