I recently downsized my turbine wheel from 2.25" to 2" to help spool-up. however i ran it on the dyno the other day and we cant get any more than 10psi out of it otherwise its pings like crazy. it makes 230rwhp @ 10psi but anything over that its just pings so we have to wind back timing and add fuel and we end up with the same power figure!
The 2 suggestions that the tuner had to offer were that it was backpressure in the cat, or the turbo is producing too much heat. I've since replaced the cat, and been to speak to the engineer who rebuilt the turbo. he says that the changes we made wouldnt have affected output temps at all, as it was only the turbine wheel that was downsized by .25"...
what else could be causing this pinging problem??