I think, and agree with previous threads made over and over again about the performance 6 prospects; it's just not going to happen. They MAY release a turbo 6, but as said it will most likely be on the smaller side and furthermore possibly to help improve economy which is the way they seem to be heading at the moment. They tried with the larger 6 years ago with the supercharged calais. But the argument still remains that to produce a reliable engine of decent size with forced induction, takes dollars. Why would holden produce a car that may cost upwards of 40 grand that ISN'T an 8? Doesn't make sense. With all the effort they have made for the HSV range (I'm not being sarcastic and referring to the clubsport vs GTS.... thats a whole different argument) I really don't think they would want to detract from their v8 sales.
Take a look when Ford did it for example when they released the xr6 turbo. That thing was a monster and yeah did detract from their other, larger vehicle sales. But it wasn't until the typhoon/tornado FPV range came out that the turbo inline 6 really started to get the publicity and EVERYONE wanted 1; who in their right mind wouldn't? More go then the larger engine brother whilst using less fuel, seems a no brainer. Ford, whilst doing amazingly well in the sales of their new baby saw HUGE losses across their v8 market. I believe thats what inspired them to bring out their new supercharged 335 boss which of course, no offence to holden cause I personally am a holden fan; but it does have alot more poke then anything holden is currently mass producing, from memory they punch out 330rwk stock and think its like 12.38 or something down the 1/4 but don't quote me on that (I don't care if you argue it, stock for stock there is no compeitition, as soon as you start getting into modding the argument changes completely). I also believe they had to make the 335 GT as good as it is to try and re-attract the v8 market and/or attract possible holden buyers to make the swap.
Long story short, I just can't see why holden would want to make the same mistake Ford did.
NOTE: I know the w427 is 380kw. I didn't count it cause what like 100 were made or something, hence i said mass produced. And lastly, the GTS vs Clubsport is a joke, the price difference between them for an 8 kw difference (Clubby being 317, GTS being 325) isn't at all justifiable. If you ask me I think holden needs to bring out an engine block, possibly even LSX that can handle massive amounts of ponies. Even if its not THAT great stock, most auto fanatics tend to mod their cars, having the possibilty to push out 1000hp by attaching 2 snails and the relative other modding would blow everything else out of the water. The downside of course is the cost to manufacture.
/rant