WTF is wrong with my car. AKA why is my boost so saggy V2
 

I previously had a thread, "Why is my boost so saggy". Which didn't yield any results. I concluded that my wastegate (Internal) was defective. Thirdgen was kind enough to let me use one he had. Excited by the thought that I would finally have power for more then a few hundred rpm I slapped it on and went for a datalog...Attached are the disappointing results that followed.

Basically I still can't hold boost.
I have;
-Switched turbos
-Switched manifolds
-Gone to a bigger exhaust
-Installed VVTuner (tried changing the settings and am currently running it on the base DIY supplied map)
-Moved my wastegate line from post throttle plate to the coldside of my intercooler
-Switched wastegate cans

I'm at all loss now. Short of an EWG and EBC. As you can see in the log it hits ~11psi by 4500 then drops to ~5.5 by redline.

Any suggestions would be appreciated.
Thanks,
-Patrick

I assume boost leak test yielded absolutely zero leaks?

I'm thinking it could be that internal wastegate flange. Ditch that and go EWG.

Correct. As far as I could tell I couldn't hear or feel any leaks. I even used a stethoscope.

Is it possible that his turbo has such a massive wastegate flap that you need a stronger iwga spring to hold it closed against the exhaust pressure?

I guess it's possible. I have this style waste gate. 5 Bolt to 2 5" V Band Turbo Downpipe Wastegate Adapter | eBay

It appears to be sealing fine just can't hold boost, I was hoping the new actuator would fix it, but it did not.

Grab a weak extension spring from from the hardware store and see if that helps the sag?

Hmm I could try that. Not sure how I'll hook a spring up. Also don't know if it matters but I couldn't even maintain 5psi

Just hook it up between the rod on the wg flapper (where the iwga connects) and the bracket for the iwga (or the barb fitting on the iwga).

have you done a "disconnect the boost control" test?

in other words, if you pull all the vac lines off the wastegate actuator and do a run (KEEPING YOUR EYE ON THE BOOST GAUGE TO PREVENT BOOOOM), does it build fast or slow?

Haven't tried, but I will. I had boost cut set at ~15psi and cranked the rod full tight once and I did hit it.