Originally Posted by aero

How far from the maf is the return tube in the intake pipe? I hod some occasional stalling issues and maf spikes when running a 2g dsm with a homemade intake. The recirculation pipe was too close to the maf and too close to perpendicular with the intake pipe. It went away wehn it was piped in closer to the turbo. Figured out it was blowing air back through the MAF the wrong way, leading to a large intermittent spike in airflow.
Is the BOV the only thing on that vacuum line, or does it share with anything else? The turbo XS valves have a very heavy piston rather than a light plate like a type-s or the stock valve so in my experience even when shimmed right, they can still cause slow response and compressor surge from the weight of the piston. Something else sharing the BOV vacuum source (like an MBC many of which have a small vacuum/boost leak) can reduce the vacuum signal and make the problem worse. All that sliding surface area makes mine pretty inconsistent in response too. I've had it freeze shut in the winter from a couple drops of water etc.

I'm not very impressed with my Type H, its a good thing it was free.

Originally Posted by slo_crx1

You so far have been the most intuitive with this type of system. The return port into the intake section is about 8 inches away from the maf, although it does have a slight angle down in towards the turbo. The valve itself seems very responsive and does hold boost well (and for the guy who posted about a ripped diaphragm, no...there is none, this is a piston style), but it works a little better now after I cleaned it and lightly oiled it. Then I pulled out the spring and stretched it a bit and added one shim. So far it's working much better. There is a good possibility of it blowing back towards the maf. The intake pipe is shaped almost like a backwards "Z", but with smooth transitions and straight up and down. I'm going to try a datalog of the load cells while under decel coming to a stop...if I can find the point where it crosses over to closed loop I can possibly lean it out a hair and see if that fixes the problem.

Originally Posted by aero

I've found the valve requires frequent cleaning and oiling, especially living on a dusty rock road. I would like to know what you find out about by logging.

You didn't mention whether the BOV is the only thing on that vacuum line.