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3-30-2012
I like the Forge. It is a simple design, that will hold as much boost as you can throw at it. My only concern is that it is apparently designed to be open at idle (I have tested and confirmed this). I think that just about all recirculating BPV's are designed this way, but I could be wrong. Being open at idle isn't necessarily a bad thing, I think it serves to eliminate compressor surge (flutter) on partial throttle lift off. But in my mind it means that it takes a split second longer to close and allow boost to build. I haven't done anything to confirm whether this is really a noticeable difference or not (probably isn't), but it "seems" better to be closed under vacuum.
Recently I've thought about trying out some other stuff. I actually put a GFB hybrid BOV on the other day. It is closed at idle and vents 50/50 recirculating and to atmosphere. It is much louder than the Forge. Unfortunately I was getting flutter during partial boost lift off no matter how I adjusted the spring. I'm told this isn't really a bad thing, but I don't really like it. I've gone back to the Forge now (after painting it). Nice and quiet, and no flutter. I think I might try the TurboXS 50/50 next.
All the Tial stuff looks really nice. The QR BOV looks pretty big though. And you need an adapter 
http://www.ultimate-racing.com/Produ...-TIAL-BOV2.JPG
I also think the TurboSmart Hybrid looks very nice. The Tial and TurboSmart are a bit more expensive though. I'm going to try the TurboXS first, and then maybe the TurboSmart Kompact BPV next. Then possibly onto the more expensive ones. Hopefully I find something I like. I think it may just come down to the fact that you either get a valve that is open/leaking at idle OR a valve that has some flutter. It may be impossible to get what I want. I'm not sure though.
3-31-2012
I decided to put my GFB Hybrid BOV back on today. I previously only had it on for a few days. I had the spring pre-load adjustment screw set to flush with the cap (where GFB recommends). At this setting it fully closed at itdle, drove fine, and blew of nicely under high boost, but it would create compressor surge (flutter) on partial boost lifts. GFB acknowledges that there may be slight flutter, and that it is nothing to worry about, but I didn't really like it.
The BOV has some external wear, but internally is perfect. I took it apart today and looked at the spring adjustments. I noticed you could back the adjustment screw out another 5-6 turns before the spring was fully extended into the housing. This made the screw stick way out. I decided to buy a shorter screw so it would have less pre-load and still be flush with the top of the cap. While I was at the hardware store I replaced all the screws with shiny new SS screws (the current ones had some corrosion).
I re-installed it (with the new screws installed). Now with the screw flush it had about 3/8" less pre-load on the spring. I started it up and was happy to find that the valve still closed at idle. Vacuum readings looked normal, and it idled smoothly. I took it for a drive and it blows off really nicely now. If I am barely, barely into boost and slowly let off, I can get a tiny amount of flutter, but hardly anything. Under normal driving (high or low boost) it opens with a nice "pssshhh".
There are some situations where it makes the "pssshhh" sound where the Forge wouldn't have made any sound. This makes me think that the Forge wasn't actually fully closed at that point. I think I'll give this valve a shot for a while although I am still considering trying a few other hybrid valves, just to see how they sound. I do like the idea of a sequential valve that would recirculate first (ie. low boost shifts) and only VTA if it was higher boost. I need to figure out which valves do this, but right now I'm pretty happy with the GFB.
