External Wastegate NOT boosting to what it set to. Where to route WG lines?

[boostadd1ct]

I have plenty of experience with turbos and wastegate set up but this has got me stumped.

set up:
holset hy35
ebay 38mm WG with 26psi spring
cast t3 (GSP)


the line is straight off the turbo compressor to hallman es MBC to side port of external wastegate.


BEFORE I went with a cast manifold I had an ebay tubular which cracked(didnt support the wastegate)

with the Tubular manifold i can adjust the boost to 30+ psi with the MBC close to maxing out(maybe like 2-3 full turn before maxing out)
with just the spring it boost at 25psi(26psi spring)


I then switch to cast due to the cracking issues.

now with just the 26psi spring it would only boost to 18-19psi.

I MAXED out the MBC and only boosting 27-28psi.

with only the manifold being changed i cant boost to 30.
any ideas?

does the cast flow that much better than I cant keep the wastegate closed? I didnt have this issue with the tubular.

Im thinking of a T at the BOV line to wastegate so it should give me more boost due to the pressure drop from the IC.(or so I think)

any drawbacks to this?

FULL boost leak to 35psi done btw.


all inputs are welcome.

ps: I know its ebay WG but It was holding up fine till I switch manifold so I KNOW it is a functioning unit.

 

[CountryDSM]

Wouldn't you have less flow with a thick cast iron manifold like a 2g manifold as you cannot port the whole thing (not sure specs on the ebay cast iron) compared to the thin fully ported through all the runners tubular manifold? Correct me if I am wrong.

 

[boostadd1ct]

F

Wouldn't you have less flow with a thick cast iron manifold like a 2g manifold as you cannot port the whole thing (not sure specs on the ebay cast iron) compared to the thin fully ported through all the runners tubular manifold? Correct me if I am wrong.

That's what it looked like to me.

But wouldn't less flow mean that it should be able to hold 26 with the 26psu spring