i would prefer a nice quiet bov any day.

most gfb bov's are to small imo. i wouldent be going any smaller than 35mm on the big 4l.

Thanks fritzz thats the sort of info I was looking for. This is the main area I was conserned about as I do not want to buy a bov that will not flow enough air to do the job.

In theory a turbo will never spin backwards when the throttle is snapped shut.[/quote]

If any of you guys where at Croyden motorsport a few years back when EB ON Boost's car blew a T04 turbo.. The shaft broke and the exhaust wheel went down dump pipe as it was spinning it cut the dump pipe like a shreader.. The reason it broke???? NO BOV!!!
I have seen my twins with NO BOV and I can tell you one will spin backwards....The bigger the intercooler and piping the more air needs to be vented also....[/quote]

That is some crazy s**t.

i got a gfb's bov on mine seems 2 b doin the job nicely

i think the GFB 'basic' blow off valve are supposed to flow well

Well I emailed Go Fast Bits and got told that the Mach 1 valve that I was looking at is good for anywhere between 250 and 280kw. They also said that up around the 12 to 14psi mark the valve would be getting close to its limit(wont be running that sort of boost anyway).

They told me that above that just run 2 of them but im not really sure I would want to go that road if I was able to get one valve that would flow enough.

I was also thinking of getting a bov setup off a skyline gtr but I think that they would charge close to what an aftermarket valve would cost anyway.

Havent heard back for Turbosmart yet but ill keep looking into their bovs.

I'm using a cheap ebay HKS knock off, the type with the purple top thats plumb back. My car has seen 20psi and regularly runs 16psi. I bought two just in case one sh!t itself as they just seemed so damn cheap (so I thought they would be crap quality). So far no problems, but I may fit the second one in tandem with the first if I ever wind it up further.

Well I ended up getting a gfb mach 1 blow off valve. So when I get it all up and running we will see how well I performs.

I had a GFB for a while.

Now I run a biggerTurbosmart.