See something that I don't really care for in the discharge air plumbing fabrication.
1) You have the by-pass valve at 90 degrees to the flow path (between the Turbo Discharge Tube and the connecting to the firewall going to the inter-cooler).
You have enough room to easily tip those feed tubes to the by-pass valves 45 degrees to the rear and then when the throttle is closed the discharge air from the turbos
would immediate exit the pipe (like an off ramp on a freeway) vs "oscillate" back and forth between the turbos and the inter-cooler tank.
Ever try to do a 90 degree with a vehicle at 100 mph? About the same deal with air passing thru the intake system at 300+ Feet per Second and the throttle blade slams shut,
and you want the by-pass air to make a sharp 90 degree turn.
So instead of giving the turbo discharge air an easy path of escape out of the pipe you have the air bouncing off the closed throttle plate pressurizing the intercooler tank
with pressure spikes while the turbo lose their speed. Good way to fail the inter-cooler tank when a simple air flow direction change could easily cure the potential problem.
I realize that you installed your by-pass valves like the picture in this Turbonetics link but the picture is not totally correct.
It just shows the basic position of the parts.
http://www.turboneticsinc.com/perfor...ructions_0.pdf
A "Off-Ramp" entry into the valve works a lot better vs a 90 degree turn.
Tom V.