In 2011 Ford gave us the Coyote 5.0L and, in the same breath, gave Mustang exhaust systems resonators. Some people appreciate a toned down note. Most of us want more flow and considerably more growl.
On the 2020 GT500, Ford did away with the worst version of that hardware and replaced it with a different problem. Here is what changed, and what our resonator delete X-pipe is worth on the dyno.
A Short History of Mustang Resonators
- 2011-2014: resonators lived in the over-axle pipes and were easily deleted with a set of Lethal Performance over-axle pipes, letting you keep the factory axle back or move to any performance axle back on the market. A full catback also eliminated them.
- 2015 and up: Ford went to a larger resonator that looks like a suitcase. It weighed a good bit and toned the exhaust down immensely. Our resonator delete pipe for those cars became a best seller, and it is not hard to see why.
- 2020 GT500: the suitcase is gone. Rejoice, briefly. Ford kept resonators in a more bullet-style design and added a large cast X-section on the same piece. They removed the weighty suitcase and replaced it with heavy pipe. Potato, potah-to.
We started development on our Resonator Delete X-pipe for the 2020 GT500 before the cars were hitting the street, working with multiple insiders to get ahead of it.
Replaces the factory resonator X-section
+7 rwhp overall, +16 rwhp peak
Uses supplied clamps, no welding
The Baseline
Our own car was delayed, which is what happens when you option the carbon fiber track pack. So we went down to Palm Beach Dyno and RareFab and did the install on head honcho Ken Bjonnes' blue Shelby instead.
We took the car for a spin, got stock sound clips, then put it on the rollers. In previous years a resonator delete generally did not make horsepower, but this was a different animal. A Predator, if you will.
The Install
Step 1: Measure and Mark
- Make sure the front OEM clamps are locked into place before you measure anything. If they are not seated, your reference point is wrong.
- Measure 30.5 inches from the CENTER of the front clamps, going rearward.
- Mark both catback pipes at that point. Those are your cut lines.
Step 2: Free the Heat Shield
Using a cutting wheel or similar, cut the four factory exhaust ties holding the heat shield above the resonator pipe. You have the option to reinstall the shield later, so take care not to damage it.
Step 3: Support the Exhaust
This step is not optional. Once you cut the stock X-pipe, an unsupported catback will sag and can damage your rear bumper or your tips.
- Support the X-section with a transmission jack or a jack stand.
- Use zip ties or similar to hold the catback pipes in place. Will at RareFab put his ahead of the mufflers.
Step 4: Cut
Step 5: Remove the Factory Section
- Loosen the front exhaust clamps with a 15mm socket.
- Remove the factory resonator X-pipe.
- Clean up and deburr the cut ends of the catback pipes. Jagged edges cause leaks.
- Remove the front clamps by unclipping them from the fastener.
Step 6: Install the X-Pipe
- Slide the supplied rear clamps over the two factory catback pipes first, before the X-pipe goes on.
- Slide the rear section of the X-pipe over the stock catback pipes.
- Install the front clamps onto the X-pipe and slide the factory cat pipes into each side. Adjust for alignment.
- Lock the clamps back to the fastener and tighten all four.
Modifying the Heat Shield
Reinstalling the shield is recommended, and it needs two modifications to clear our X-pipe.
- Cut the front section off the shield so it clears the X-pipe.
- Drill a hole into the first dimple so the supplied stainless exhaust ties can clip through and attach to the X-pipe.
- Place the shield back over the X-pipe and secure with the supplied ties.
Worth knowing: the section you cut off still has another factory heat shield behind it, so the driveshaft keeps its protection where it needs it.
Dyno Results
Back to Palm Beach Dyno, same day, same conditions, which is the only way a before-and-after means anything.
| Measurement | Result |
|---|---|
| Stock baseline | 676 rwhp / 556 rwtq |
| Overall gain with the X-pipe | +7 rwhp |
| Peak gain | +16 rwhp at 6,645 rpm |
Be honest about what that means. Seven horsepower overall is a modest average gain. Sixteen at 6,645 rpm is where the restriction actually was, and that is the part of the rev range a GT500 owner spends money to reach. For a bolt-on that also transforms the sound, on a car where most resonator deletes make nothing at all, that is a good result.
Hear It: Ken's Full Review
Numbers are one thing. Ken Bjonnes walks through the setup with before and after sound clips, which is the part you actually buy this for.
Frequently Asked Questions
How much horsepower does a resonator delete add to a 2020 GT500?
On Ken Bjonnes' stock GT500 at Palm Beach Dyno, 7 rwhp overall with a peak gain of 16 rwhp at 6,645 rpm. That is unusually good for a resonator delete, which on most cars makes no measurable power.
Where do I cut the exhaust for a GT500 resonator delete?
Measure 30.5 inches from the center of the front clamps, going rearward, and mark both catback pipes there. Confirm the front OEM clamps are locked into place before measuring.
Do I need to cut my factory exhaust to install this?
Yes. This is a cut-and-clamp install into the factory catback. No welding is required, but the cut is permanent, which is why the measurement matters.
What tools do I need for a GT500 resonator delete?
A cutting wheel for the exhaust ties, a sawzall for the pipes, a 15mm socket for the factory clamps, a drill for the heat shield modification, plus a jack or stand and zip ties to support the exhaust.
Do I have to reinstall the heat shield?
It is recommended. You will need to cut the front section off and drill a hole in the first dimple so the supplied ties can secure it to the X-pipe. The driveshaft still has an upper shield behind the part you remove.
Does a resonator delete require a tune?
No. This is a bolt-on exhaust change and does not require calibration.
How loud is the GT500 with a resonator delete?
Meaner, noticeably. It is not a straight pipe, since the factory mufflers and cats stay, but it removes the piece Ford put there specifically to quiet the car down.
Is this install something I can do at home?
Yes, with a lift or good stands and the right tools. The risks are cutting in the wrong place and cutting into the fuel tank or the carbon fiber driveshaft, both of which are avoidable with care.
Keep Reading
Delete the Part Ford Added to Quiet It Down
3" T304 stainless, developed before the cars hit the street, and it makes power on top of the noise.
