2L8LUZ

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Dcasole

Are u sure they are closing ?

I have NPP in a box , this is is where they are open or closed ...when opened I get a ton of Decel pops and cackle .......

With a true NPP system your valves were closed most of the time especially on decel so you would not have heard this

Dave

Dcasole

When mine are set to closed .... I dont hear anything ......

Dave

Suns_PSD

You have a stage 4 cam, which means you are not going to have vacuum pressure, and vacuum pressure is required to operate your NPP Muffler. It's not going to work correctly with that cam.

Dcasole

True but if he makes enough vacuum to operate his power brakes there should be enough vacuum on decel to close the mufflers ..... cam or not during acceleration the valves will open.......

Dave

CI GS

I've run it both ways, and I didn't have any backfiring, nor could I detect that the valves closed quicker without the solenoid? The solenoid is basically a shut off valve that controls the vacuum going to exhaust, so I don't understand how that would slow down the closing of the valves. What makes you think it's closing quicker? I think you may still have a very slight exhaust leak?
BTW: the solenoid bypass doesn't - can't, actually - introduce air/oxygen to the exhaust tract, since the vacuum is only supplied to the sealed diaphragm canisters that operate the bypass valves.