Here is the thing about the magnum xxxl and the viper and the other monster hoods... they are fucking stupid. Yes, I said it, they make absolutely no sense at all. The reason is pretty simple really, but apparantly not simple enough for those that flock to buy these things because somehow bigger is better or they are going to somehow "stretch the light out". The fact of the matter is that light emits from the SIDES of the bulb, not the ends. Little to no light comes out of the tip of a bulb and no light obviously comes out of the socket end. So you have a 15" long surface (for a 1k HPS) that is giving off light. It strikes the SIDES of the reflector and is cast down. Sure, some light is radiating at an angle off the bulb, but the vast majority of the light is cast in a pattern that is a couple of inches wider than the bulb is long. Sooooo, when you put a 15" bulb in a 39" long reflector (raptor) what do you get... you get a whole lot of sheet metal not really reflecting much of anything. Even on moderately shapped hoods you really start to loose lilght once you get away from the bulb. Hell, my AC hoods are hung about 6" away from each other to create an even, high strength field of light. If I ran magnums I would have to tape them end to end and there would still be big parts with low light. I've seen videos about it, I have seem them running in the store, and I have used my lux meter under a magnum at my buddies house. They are quite simply big, heavy as fuck and expensive for no reason at all.
Take a look at the greener's AC hood test...
http://www.greners.com/reflector-test.html
You will see that over a 4x4 area (which is generally the lower limit of really effective light for a 1000w bulb) low and behold, you will see that the blockbuster (which is my recomendationa nd not because I just bought 6 of them), has a HIGHER lumens on the permiter AND higher in the center than the magnum. So what you are seeing is that a 25 x 25" reflector that weighs about 10-12 lbs beat the shit out of the monster 30" x39" 30lb hood.
So, now that the rant is over, my recomendation for hoods (and I REALLY REALLY geek out on hoods dude, I bought 5 different hoods initially and returned 4 before outfitting my first room) is that if your going to run 1k bulbs, nothing beats the blockbuster 6". If your going with 600watts I would say either the blockbuster again or the super sun II. People still spooge all over the performance of the super sun II and rightly so. Its a tiny and shallow hood but JESUS does it throw the light down. It is definetely narrower than the blockbuster but if your going for penetration, it can't be beat. Too small for a 1k in my eyes, but people do run them.
The new blockbusters are VERY well made. Nice thick seals, tumb screw that actually clamp the glass closed and SEAL it (no more taping the damn hoods for sealed room running), and wires on each side to prevent the glass from swining all the way down and smashing your plants when its mh to hps time.
check out the greeners link and if you REALLY have time, the massive ICMAG thread on hood tests...
http://www.icmag.com/ic/showthread.php?t=51325
You generally can't get great air flow AND quiet without doing some add ons yourself. enclosing the fan in a foam lined 3/4" MDF box, and using a muffler on the other end will make it virtually silent.
Cheers dude and good luck.
