It looks so simple in function. How could it possibly be that expensive to make?

 

They are made by Sound Performance. A new 4" valve costs $450 without the flanges that are 35 each. The valve is all stainless. They open instantly when the predetermined boost is reached. In my case 11 PSI. They are the same people that make the spool valves. There is a vid on youtube that shows how quick it opens.

 

Here is the video of it working. This video is when they first started making them and they were experimenting with welding V bands on them instead of 3 bolt flanges. Now they only make the 3 bolt flange version. I had been debating one of these for a while now.

SP boost activated exhaust cutout - YouTube

 

That ought to make tuning a big PITA for you.

 

Wow this looks like an awesome Idea though... I love it. Where did you get it from?

They make it sound on the website like its a gradual open... if it were a more instant open like you make it sound I would be all over it... but I dont want it cracking open at 5# boost when getting just a little aggressive around town.

 

Roger,

Not sure how tuning will be. I bet if I was shooting for 11 PSI where it opens it would be a pain. Time will tell. hopefully my flanges show up this week so i can get it hooked up.

I got it off of another forum. I think it might open gradually if I was boosting at 11 PSI. Since I am much higher I think it will open up quickly. I might take some vids of it when I get it all hooked up.

 

Interested to see how it works out. Hope you document it for us!

 

Its funny because 11# is right around where I plan to end up... I read about it and they said it starts to open at 5#, is 90% open at 7-9# and takes 11# to open completely.

I would think with a turbo build that plans on much more than 11# of boost you will be hitting 5# regularly... might get annoying. I love the idea of it, I'm just really curious to see how it will work

 

Im curious too. I wasnt aware it opened gradually at 5. I assumed it started opening at 11, and was opened up by 15 or so. I will more than likely be around 22 when my truck is all done. I do hit 5 quite often. I will start a thread in the exhaust section when I get it going.