Getting more for the MKIII- stock

[Grandavi]

Havent had the car long enough to tell if the cable is broke or just not put on. Most of the car is a bit of a hack job although done pretty decent. Like.. now I have a problem where the door ajar light is stuck on.. but I think that may be moisture related somewhere in the electronics. I will fix the speedo cable if I start working on the car, currently it is slated to be a donor car, but my kids are very adverse to my taking it apart after I took them for a spin in it.

I dont quite understand the wastegate though. I have to research where it is on my car, and if its something I should look at upgrading (current plans are to put a 57 trim CT26 upgrade on it after its painted). I understand its purpose (mostly) but when i went to look for it, I got confused.. (I am an old fart.. so thats easy to do).

researched the boost controllers and a cheap T-type seems to be all I need to open up the turbo more.

Have been researching BOV's but some are purdy and some may have a nice sound, but I want a bit of noise when it kicks. Not sure which one is a good option really (just a simple bolt on that looks good and does the job.

The stock exhaust has issues (small ones like the turbo elbow restriction) and I have 2 cars running 3" exhausts on them now.. the 90 is the quietest so I may just swap exhausts and that problem will be solved providing it is from the turbo back. Not sure if I have a custom DP on the 90 yet as its under a car cover and I haven't seen it in a couple months. Im stuck on buying a new stainless steel 3" with DDP or using one off of my other 2 cars.

All in all though, if I drop the 3" exhaust on it with a DP (not divorced if I see it correctly on my 87), push the turbo to 12 psi, what is the HP estimate that I will be getting at the wheels? 250-265?
(with the stock fuel system and AFM)