I had a Powerplay ROM tune for a fair while, two actually. I got them cos I had an auto R34.
The first got me from 162rwkw to 189rwkw but was faster than the raw numbers represent. This stage was the best value and the one I would most recommend. That was stock turbo and full exhaust.
Second stage was highflow turbo and 480cc injectors. Got 228rwkw at 0.9 bar. I passed an R34GTR down the Eastern Creek straight (only just) that had been tuned (PFC) the day before at Croydons and had 250awkw.
I got fairly poor fuel economy with this tune.
Next I put some Tomei Poncams in and without a retune and at the same boost I got 255rwkw. It ran ridiculously rich in the midrange and was pretty bad on fuel too.
Then I did a manual conversion with PFC, running 1.3 bar and getting 272rwkw.
In short, with stock turbo at stage one I think it was worth the money. Also, I got the very first one. I'm sure they would have refined it since then.