How can you tell from those photos? You'd really need to measure the exducer diameter to know for sure
Its no real surprise that your turbos are better all-round performers than this one. Remember that yours were designed as a complete package by garrett, but the ATS turbo has the wrong wheels for the housings (despite the fact they are machined to fit)
That's the compromise for having things looking standard i guess.
The same wheels in the right housing would no doubt bring on boost sooner and go on to make more power, but then he would need to worry about manifold to comp housing clearance, external gate and lots of other non-standard things
Also no doubt you guys have the newer generation comp wheel, whereas the ATS one has the old-school T04S wheel