This is just an exhaust cutout, it goes just behind the cat and basically just acts as a straight through pipe. The ATP Cutout is activated when the turbo (or supercharger in our case) hits boost. So basically it would be open all the time. However another company called QTP makes the same thing with the exception that the flange opens with the flip of a switch, so only when you feel like opening it. This could be a great alternative for those looking to buy a catback. Below are links of both.

ATP Cutout - ~$235

QTP Cutout - ~$190

What do you all think of this?

 

I always wondered what happened to these things. I remember JC Whitney used to sell a cable-operated one that connected to a **** on the dash. Didn't used to cost two hundred bucks, though. More like $16.95?

:smile:

 

Yea they've really gone up in price. No one else has anything to say about this?

 

I'd want to see dyno charts for this on a small-displacement car before I'd go this route. Some cars actually suffer a loss of torque when run with what is, essentially, an "open header." What works for elephants, rats, and tunnel-ports doesn't always work for hamsters.:smile:

 

Haha nice. I don't think you would suffer much torque loss, in fact i think you'd gain torque as well as hp. Because theres no resonators or mufflers the air has to pass through, so it'd be just like an extremely free-flowing cat-back.

 

Dunno why, but some back pressure is a good thing. Or so I hear.

 

Having some resistance is good for torque, at least in many of the applications that I have experimented with. SuperTrapps are a great example of this. On my dune buggy (with ST), I get more low-end gusto by creating more restriction, or back-pressure by removing discs. This is typically at the expense of output though...

 

Using a MBC inline with the cutout, it could be set up to only open at a certain boost level, so that the stock sound and backpressure are intact up to, for instance at 13 psi (5,000 rpm) with a 15% pulley:



The VW Golf R32 has a similar exhaust switchover valve.

 

This might make a nifty active modification to the "one-ball" concept. At the "Y" split usually found in parallel-flow dual muffler cat-backs, in place of one of the mufflers, install the cutoff valve, and plumb a section of plain mandrel-bent pipe back to the rear of the car. One exhaust tip is attached to the remaining muffler, the other is connected to the new section of pipe. As you suggest, nice and quiet, until the driver (or an RPM-controlled actuator) flips the switch to open the valve. From the rear, the car just looks like it has an ordinary one ball cat-back. And, the valve can be disabled via a hidden switch for those times when its best to be seen but not heard.

"To what loud noise are you referring, officer? There's no polished-stainless coffee can strapped under my bumper. You can even go for a spin around the block with me to hear for yourself, if you wish!"