Electronic or Manual Exhaust Cutout?

Short answer: if you will open it more than a few times a year, buy electronic. If it is coming open at the track and staying shut the rest of the time, a manual kit does the same job to the exhaust for a lot less money.

What a manual cutout actually is

A manual cutout is a flange in your exhaust with a cap over it. To open it you get under the car and undo the cap by hand. That is the whole mechanism, and the simplicity is the point: there is no motor to fail, no wiring to run, no switch to fit, and nothing that can jam halfway.

What it costs you is convenience. Opening it means jacking the car or crawling underneath, and that is a decision you make in the driveway before you leave, not on the road when you fancy it.

What an electronic cutout does differently

An electronic cutout puts a motor on that valve and a switch in the cabin. Open and closed becomes a decision you make at a set of lights rather than on a creeper. Granatelli systems use a one-touch switch, and a wireless remote is available if you would rather not run a switch into the dash at all.

That is the entire difference. The hole in the exhaust is the same hole. What you are paying for is access to it.

So which one

Buy manual if

The car is a weekend or track car and the cutout opens on race day and closes when you load up. Or you are on a tight budget and would rather put the difference into the exhaust itself. Or the car lives somewhere the roads are salted and you would rather not have a motor and a loom down there at all.

Buy electronic if

The car is driven on the road and you want it quiet past the neighbors and loud on the on-ramp. Or the cutout is going somewhere you physically cannot reach without jacking the car. Or you are fitting duals, where opening two caps by hand gets old fast.

The third option most people miss

Granatelli also builds vacuum and pressure-controlled systems, which open and close using the engine's own vacuum or a pressure source rather than an electric motor. They suit builds that already have an air or vacuum system plumbed in, and installations where running electrical power to the cutout would be awkward.

What people regret

The two complaints that come up are opposite and both avoidable.

People who bought manual to save money often wish they had not, because in practice they open it far less than they imagined. A cutout you never open is a heavy flange in your exhaust.

People who bought electronic sometimes find the motor sits somewhere it takes a beating from road spray and debris. Mounting position matters more on an electronic kit than a manual one, because there is something down there that can be damaged. Think about where the motor will hang before you commit to a location.

Reading the part number

You can tell which is which before you click anything. Manual kits start 305 or 306. Electronic kits start 302, 303, 307 or 313. After that the two digits are the size — 25 is 2.50", 30 is 3.00" — and a letter on the end marks a dual kit.

Whichever you pick, get the size right

Both types are sized to the outside diameter of your exhaust pipe, and both are sold in the same five diameters. If you have not measured yet, start with what size exhaust cutout do I need — it is the mistake that causes returns.

Ready to choose?

Shop all exhaust cutouts, or go straight to the manual kits if you have already made up your mind.

Not sure? Call 1-805-486-6644, Monday to Friday, 8am to 5pm Pacific. We build them in Oxnard, California.