Evaded

The HDI Boost Controllers are quite a reasonable base model electronic boost controller however quality I was a little weary of. In my case one of the adjustable knobs failed and basically did nothing. I never bothered fixing it as shortly after that I pulled my car off the road and it didn't have the features i needed. Basically work out the boost you want to run, work out the features you would like it to have, narrow it down to those options then work out which one you want. Asking such a broad question isn't going to get you the best answer. As a few others have said I quite like the Blitz ID-III as well. But it depends on your application and budget you might not need to go that overkill.

That charger is only rated to 825hp. You will be running it right on it's very limits to be able to produce 500rwkw in fact there is an M3 running that same blower and it is only making 460BHP, although I am not sure at what pressure they are running it at.

SC14 is too small to be really effective on an RB25DE as well. MissR34 are you chasing 750hp at the wheels or at the engine. Either is a massive power output. I assume you are running one of the Vortech V1, V4's or V7's. I hate saying it but I don't think you will make the power levels you are after however good luck chasing them. Either say with half the power it would still be a great car to drive.