I'm wondering if my numbers are low? I was expecting a bit more power (400hp or so) Any thoughts?

Car was tuned at 25psi on 93 pump

ATP stock location GT3071r turbo
Stock turbo manifold
Stock o2 housing
Buschur Turbo back exhaust with test pipe
GSC stage 1 cams
ETS 3.5 intercooler and pipes
880 injectors
Walbro 255lph pump
ETS intake
Hallman MBC

What kind of dyno was it

Is this after tuning? It looks very squirely at the end with a dip and then more gains again

Dynojet

Tuner said the dips were due to the stock o2 housing and manifld

looks like the power is a bit on the low side

You do realize this turbo is smaller than a stock 9 turbo correct???? It's litterally marginally bigger than your stock turbo.......my correction not smaller but arguably the same size as an evo 9 turbo...

I think these two things are hurting you a LOT more than you think.

manifold... nah. O2 housing, yes! That turbo needs room to breath!

I got the turbo for free, no shaftplay so I can't complain on that end.
I will be getting an Aftermarket o2 housing and getting the stock manifold ported.
Or what would be the best route.

who tuned it?

Pretty much nailed it on the head. OEM ported is one of the better alternatives to go with! and an o2 housing for sure

i got a stock exhaust mani i can sell you if you want to limit your down time! let me know

Was tuned at Moore auto in Fairfax VA

Thats low on for 25 PSI. Mine has Tomei and only at 22 PSI it makes 324 on mustang dyno.