I had one.
On the dyno it pinged a bit at tq peak but still wanted timing up top. From what I've seen good A/F and less back pressure are te key. In fact thats what a lot of smart people told me. That's 10psi and up top the internal wastegate fluttered so it got all wavy. Done at unnatural last April on a very rainy day. Cool and humid.
UK highport 10:1. GtiR T28 kit, 370s @4-bar N60 set up blow-thru, 3" turbo back FMIC.
I burned a rod bearing at PIR. WOT in 4th the bolt walked off my rotor/distro.