Getting more for the MKIII- stock

[Grandavi]

This is stupid question time... but my 88 is a 7MGTE and bone stock except the rad (got it while I had coolant changed, is the KOYO aluminum one). No 3" exhaust yet, although I have 2 available on my donors. Boost is stock, the only addon related to the engine is a turbo timer (just using it for cool down).

So.. I have questions. First, I own a 87 that has a really nice 3" exhaust and Megan DP on it, boost controller and the waste gate is shimmed I believe. I get a whistle when I start out which I thought was initially the fan belt, but now I think its a vacuum leak. Did the previous owner shim the waste gate for faster spool? (all the cars I own btw are 7MGTE)

Second, to begin with, all I think I need is a boost controller (would be nice to have a boost gauge to put inside the car as well) to up the boost from stock to 10-12 psi. Correct? The 3" exhaust is a given so I wont discuss that yet, unless there is something relevant that I should know other than it lets the car breathe better...

I dont need to focus on the FCO (adding Lexus AFM, 550 cc low imp injectors, or fuel pump) unless I go with a larger turbo. Correct?

The stock BOV is fine, or should I upgrade that? (not sure if its needed for performance, looks or sound ..)

Finally.. I have a JDM Supra JZA70 rear-end (LSD), does anyone know the gearing on this? Just wondered what it is compared to the stock one in my 88 to decide if I am going to swap this in or not...

Found this...
Other features of the JZA70 Supra was the replacement of the mechanical clutch LSD with a Torsen unit. The final ratio was also changed to 4.11 compared to the 3.73 of the MA70..
so now I have to go look and see what mine is on the 88... probably the 3.73. Not sure which is more desirable.. (going to read now.. )

Thanks in advance!