I have an electronic exhaust cutout on my car and recently had it tuned with stock compression. At 6psi, i made 325whp with the cutout shut with stock exhaust, with the cutout open, and the boost slowly creeping to 7psi at redline i made 375whp. I personally like the cutout being controlled electronically because i sometimes like to cruise with the cutout open, as well as going WOT with it shut. With o2 feedback, my a/f ratio stays safe in both situations.

 

Those are some nice gains.

I just purchased my exhaust cut out on ebay. Size is 10 inches with the flange on the side.

With the boost activated cut out using a waste gate type syste, if I were to have it set at a low psi, like 3-5, would this make it more efficient.

Im currently running 9psi, so when I would start to hit it, and the boost rises, once it hits lets say 4 psi, the exhaust will open up.

 

Mine started to open at 3-5PSI and was full open aroun 10PSI

 

I picked up close to 50 hp over the stock exhaust with the cutout in place of the cat converter.

That was an old setup, with a rehard mani.

I now have the cutout on the vertical portion of the down pipe, at the base of the firewall, using a side winder style mani.
I didn't have a cutout open vs closed comparison on this, since the cutour opens automatically.

 

For these boost actuated cut outs, is there a spring to Change when it you want it to open sooner or later or does it start automatically once it senses boost?

 

Exactly the same reason I like my Elec cutout


Also to me, I get the biggest thrill out of opening the cut out before I start the car, something about starting the car with the cutout open, just sounds like a monster, all burblely and throaty, haha