Changed the turbo housing and I get crazy LAG..WTF . Chime in please!

[SupraClaou]

I have an ITS 72mm DBB turbo with a .70 A/R divided housing on an HKS GT divided
exh. manifold. Some days ago I got a .84 A/R rear divided housing (heat coated) and
I put it on!

With the .70 A/R I had full boost (external opens) at 4.500 rpms / 18psi max boost.
With the .84 A/R I get full boost around 5.000 rpms / 18psi max boost.
If I turn the boost controller (around 11 psi spring rate on the WG) off , it seems
to spool for ever and I get full boost around 5200-5300 on 2nd gear.

Two things should be noticed here,which made me wonder :
1) The rear housing is a Comp turbo unit which we all know is an interchangable unit with
the ITS one...at least that's what they say.
2) When I did install the Comp 0.84 A/R housing it seemed the wheel had more gap till
the housing wall. Around 0.5mm I should say.

Did I miss something here?
Please chime in and tell me your thoughts.
CAR IS UNTUNED with the 0.84 a/r housing. I wanna tune it and it needs tuning from what I know,but I don't want to spend tuning money on something sooooo laggy.
Never thought an .84 a/r would have such a big difference compared with the 0.70 a/r.

 

[Supracentral]

A change to a .84 A/R from a .70 A/R should only change your boost threshold by about 100 to 200 rpm with that turbo.

Sounds like you've got a turbine housing that doesn't actually fit your exhaust wheel.

What are your power goals and driving goals with this car that make a .70 unsuitable?

 

[SupraClaou]

A change to a .84 A/R from a .70 A/R should only change your boost threshold by about 100 to 200 rpm with that turbo.

Sounds like you've got a turbine housing that doesn't actually fit your exhaust wheel.

What are your power goals and driving goals with this car that make a .70 unsuitable?

This is what I was afraid of...wrong turbo wheel trim on the new Comp turbo housing. Damn...
Around 700 whp and 26-27 psi of boost on 100 octane gas is my goal.
The .70 A/R housing seemed to run out of air around 7200 rpms,but I had full boost at 4500 rpms.