Hey mate,
I've so far had the car back at 3 power levels. 298,312 & 335awkw
Compared to how I first got the car back in 2005 (standard ceramics boosted to the max - 260rwkw), the -9's are definitely a bigger turbo and respond accordingly. The -9 setup in my car pulls all the way pretty much to redline unlike the standards which hit a wall near the top end. (and you could feel it)
Depends what you're after- purely street i'd go -7's for a 2.6L. I want to eventually get some events under my belt so wanted that little bit extra so went -9's as I had all the supporting mods.
That said look at gtr jet, he got 325kw with his -7's. Awesome.