Oleg's description to picture wasn't accurate but he meaning was assuming we know what the GT35r impeller looks like.
The one on the left is the HTA and the right the GT35r.
The HTA is billet, has an extra but still lighter hence the 500+- rpms depending on tune.
Oleg, why don't you give us some additional info on the HTA since you're the only one that's tested them.
It's been a while since your last post and people may have missed it.
I think he gained 7~8% more power (HP and TQ) across the board just with compressor swap with no retune.