Exhaust Cutout FAQ

An electric exhaust cutout is a motorized valve welded or clamped into the exhaust ahead of the mufflers. Closed, the exhaust runs through the mufflers as normal. Open, part of the exhaust exits through the cutout's turndown for a louder note and less backpressure. A Granatelli electric cutout opens or closes with one tap of a switch or wireless remote. See how electronic exhaust cutouts work.

Granatelli Motor Sports, a performance parts manufacturer in Oxnard, California. We design and sell electric, vacuum/pressure-controlled and manual exhaust cutout kits in 2.25", 2.5", 3", 3.5" and 4" round sizes and a 3" oval size, in single and dual configurations, and we support them directly by phone at 1-805-486-6644.

Look at five things: how the switch works, what the motor and gears are made of, what the valve is made of, whether the kit is complete, and the warranty. Granatelli electric kits use a Smart-Chip one-touch rocker switch (tap once, no holding the button) with auto-stop to protect the gears, a high-torque DC gear-reduction motor, heat-resistant carbon steel gears, a stainless steel butterfly plate and shaft, and a CNC-machined 6061 aluminum body. Each kit includes the turndown, V-band clamp, gaskets, wiring harness, switch and hardware, and you can add 1-, 2- or 3-year extended coverage at checkout.

The cutout, a polished stainless steel 45° turndown, a V-band clamp, gaskets, a wiring harness, a one-touch rocker switch and all mounting hardware. Dual kits include two cutouts, two turndowns and the harnesses to run both from one switch. The 3" oval kits (313530 and 313530D) also include an oval-to-round adapter.

Buy electric if you want to open and close the exhaust from the driver's seat with one switch. Buy vacuum/pressure-controlled if you want wireless-remote control and a system that brings its own vacuum pump, so it works the same on boosted and big-cam engines. Buy manual if you only open the exhaust at the track: you remove a block-off plate by hand, and there is no motor or wiring. More detail: Electronic or Manual Exhaust Cutout?

Round cutouts in 2.25", 2.5", 3", 3.5" and 4", and a 3" oval cutout for oval exhaust tubing. Match the cutout to the outside diameter of the pipe at the mounting point: a 3" pipe takes a 3" cutout. Read What Size Exhaust Cutout Do I Need?

Only the Y-pipe and/or the hold-down clamps on slip-fit kits. The cutout itself is the same in both: the CNC-machined 6061 aluminum body, stainless steel butterfly plate and shaft, motor, gears and polished stainless turndown. Mild steel costs less and suits track cars and vehicles kept out of the weather; stainless steel resists rust, so choose it for a daily driver in a wet or salted-road climate.

Slip-fit (clamp-on) kits clamp onto the cut pipe, so most installs need only hand tools and a way to cut the pipe. Weld-in kits are welded into the exhaust for a permanent, leak-free joint and need welding equipment or a muffler shop.

Use a dual kit on a true dual exhaust, with one cutout on each side. Dual kits run both valves from one switch. A single exhaust, or a dual system that merges into one pipe, uses a single kit.

Yes. The 303510R wireless remote is for single Granatelli electric cutouts and the 303510R-D is for dual kits. They plug into the existing Granatelli cutout harness, work from inside or outside the vehicle, and are compatible with supported vehicle Homelink systems. Vacuum/pressure-controlled kits include a wireless remote.

No. Granatelli vacuum/pressure-controlled kits include their own vacuum pump, vacuum control box, lines, fittings and a wireless remote, so they work the same on supercharged, turbocharged and big-cam engines. They come in 2.5" and 3", single or dual, slip-fit or weld-in.

Yes. Granatelli manual kits use the same style of cutout, and you can add a motor later. Call 1-805-486-6644 to confirm the parts for your size.

Yes. The 313530 single and 313530D dual 3" oval electric weld-in kits fit Granatelli 3" oval exhaust tubing and include an oval 45° turndown and an oval-to-round adapter. See the Oval Exhaust Tubing FAQ.

Opening the cutout reduces exhaust backpressure ahead of the mufflers. Any gain depends on your engine, headers, exhaust and tune, so we do not quote a fixed horsepower number. Read Do Exhaust Cutouts Add Horsepower?

Many states, including California, prohibit exhaust cutouts on vehicles driven on public roads. Keep the cutout closed on the street and open it only at sanctioned off-highway events. Never install a cutout upstream of a catalytic converter or use one to bypass emissions equipment.

Electric, vacuum/pressure-controlled and manual exhaust cutout kits carry a 90-day limited warranty. You can add 1-, 2- or 3-year extended coverage at checkout. For a claim, contact us with proof of purchase and the part number.

Orders placed before 3:30 PM Pacific ship the same business day, and website orders over $100 ship free.

A size transition or custom fabrication may be required; a mismatched cutout is not a direct fit. Match the exhaust's measured outer diameter and the kit's connection specifications.

Mount it at least 18 to 24 inches after the catalytic converters and away from any O2 sensor. For the best sound, mount it after the X-pipe or H-pipe, and aim the turndown toward the rocker panel, away from fuel and brake lines. Our guide covers this in detail: Where Should You Install an Exhaust Cutout?

Yes, in most cases. A slip-fit kit clamps onto the pipe, so you need basic hand tools and a way to cut the pipe. A weld-in kit needs welding equipment or a muffler shop.

No. Never install a cutout upstream of a catalytic converter. Mount it at least 18 to 24 inches after the converters.

Potentially, if there is sufficient space and the tubing size and layout suit the selected kit. Check local road-use requirements and have the exhaust placement inspected before fabrication.

Avoid any orientation that exposes the actuator to impact, debris or water beyond its installation requirements. Confirm the allowed mounting orientations in the kit instructions.

Clearance depends on the cutout size, valve style and turndown or pipe attachment. Check the dimensions and move the valve through its full travel before final welding.

Follow the kit's mounting design and provide adequate exhaust support. Excessive vibration or the weight of unsupported piping can stress the valve assembly.

Yes. Temporarily position and cycle each valve as the kit allows to verify full travel, connector access and chassis clearance before permanent fabrication.

Install and torque hardware as directed, then inspect it after heat cycles. Use only a thread-locking product suitable for the location if the instructions recommend one.

Choose a secure location compatible with the kit's environmental and temperature limits, protected from exhaust heat, moisture and mechanical damage. Follow its mounting instructions.

No. The Smart-Chip one-touch rocker switch runs the valve through its full travel with one tap and stops the motor automatically to protect the gears.

Follow the kit and vehicle electrical safety instructions; disconnecting the battery is generally appropriate before modifying vehicle wiring. Use the specified fuse and wire routing.

No. Install power and circuit protection as directed by the exact kit instructions. An unprotected wire can create a fire risk if it shorts.

Select Granatelli control-box configurations support two valves; confirm the controller and kit part numbers before connecting a second actuator.

Do not replace the supplied control logic without confirming compatibility. Automatic-stop and motor-protection functions may depend on the designated controller.

No. The remote communicates with the system's compatible controller; it does not replace required motor power, wiring or circuit protection. See wireless remotes and switches.

Use an extension only where permitted by the kit instructions, with suitable conductor size, insulation and sealed connections. Excess voltage drop or poor joints can affect motor operation.

The driveshaft and suspension can move or rotate into nearby wiring. Secure the harness clear of all moving parts with enough slack for suspension travel.

A downward loop can help prevent water from traveling along a wire into a connector or enclosure. It supplements, rather than replaces, properly sealed electrical connections.

Route the harness on the protected side of the chassis, use specified clamps and maintain the kit's heat clearance. Avoid routing near the valve outlet or other hot exhaust surfaces.

Control features differ by kit, so use only the operating modes specified for your switch and actuator. Do not force or hold the motor against an end stop.

With the exhaust cool, inspect for debris, interference, loose hardware and binding. Check the wiring and run the full open-close procedure in the product instructions.

For applicable kits, cycle the valve fully open and fully closed three times as part of the recommended reseating check. If it still binds or leaks, stop and contact support.

Allow the system to cool, check power and connections, and inspect for valve binding. Follow the kit's reseating procedure; stop if the actuator stalls or overheats.

A valve that will not seat needs inspection for debris, alignment, actuator travel and mechanical damage. Do not assume backpressure is the only cause.

Heat-related binding, hardware movement or an electrical fault may be involved. Record whether the issue occurs hot or cold and inspect the valve and wiring when safe.

Inspect the installed fuse, ground, switched power, controller and wiring under load. Use the kit's wiring diagram and avoid bypassing its protection circuits.

A circuit may read normal voltage at rest yet drop excessively under motor load. Follow the wiring diagram and use a qualified technician if electrical testing is unfamiliar.

Check the second motor connector, its harness, controller channel and valve movement using the applicable diagnostic procedure. Do not swap wires between channels unless the kit instructions allow it.

Yes. A pinched or abraded harness can interrupt power or short to the exhaust. Repair or replace damaged wiring before further operation.

With the system powered off and cooled, inspect connectors, wiring and the actuator for water intrusion or corrosion. Follow the product's environmental limits before operating it again.

Send the cutout and controller part numbers, installation photos, a short video of the fault, wiring details and whether the valve moves freely when cool.

Show the switch or remote command, which valve moves, any actuator sound and the controller indicator if present. Keep hands and the camera clear of hot or moving exhaust parts.