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A Reversible Straight-Through Glasspack With the Classic Deep Tone
This is the MagnaFlow 18125, a universal glasspack muffler with a 3.5 in round body, an 18 in body length and a 22 in overall length. Inlet and outlet are both 2.25 in and both centred, and the straight-through core is single-stage packed to produce the deep tone glasspacks are bought for.
Key Features
- Reversible straight-through glasspack core, so it can be installed with flow in either direction.
- Single-stage packing for the classic deep glasspack note.
- 3.5 in by 3.5 in round body with an 18 in body length and 22 in overall length.
- True 2.25 in center-in and 2.25 in center-out configuration with a single outlet and no tip.
- Corrosion-resistant aluminized steel body with an aluminized finish.
- CNC robotic manufacturing for consistent seam and core placement.
- MagnaFlow explicitly warns to check local noise regulations before fitting a glasspack.
Fitment
| Specification | Value |
|---|---|
| Fitment type | Universal, not vehicle specific |
| Inlet | 2.25 in, centred |
| Outlet | 2.25 in, centred, single outlet |
| Body | 3.5 in round, 18 in long |
| Overall length | 22 in |
| Typical applications | Cars, trucks and SUVs with a 2.25 in exhaust, fitted as part of a custom exhaust |
This muffler carries no vehicle fitment. It is selected by pipe diameter, body clearance and desired tone, and it requires custom exhaust work to install.
Specifications
| Detail | Value |
|---|---|
| Brand | MagnaFlow |
| MPN | 18125 |
| Series | Glasspack |
| Type | Glasspack |
| Internal construction | Straight-through, single-stage packed |
| Material | Aluminized steel |
| Body finish | Aluminized |
| Body shape | 3.5 in x 3.5 in round |
| Body width | 3.5 in |
| Body length | 18 in |
| Overall length | 22 in |
| Configuration | Center in, center out |
| Inlet and outlet size | 2.25 in / 2.25 in |
| Outlet quantity | 1 |
| Outlet style | Standard, no tip |
| Hanger included | No |
| Package dimensions | 26.80 x 4.90 x 4.60 |
| Warranty | 90-day limited construction warranty |
What's Included
- One MagnaFlow glasspack muffler
- Gaskets and hardware are not included
About MagnaFlow
MagnaFlow's glasspack range is the simplest silencer the company builds: a perforated straight-through core wrapped in packing, with no chambers and no restriction plate. That construction is why glasspacks flow well and sound the way they do, and why they are usually welded into a custom system rather than bolted into a factory one.
FAQ
How is a glasspack different from a chambered muffler?A glasspack runs a straight perforated core wrapped in packing material rather than internal baffle chambers, which is why the body is a simple round tube with matched inlet and outlet sizes.
Is it a chambered muffler?No. It is a straight-through glasspack with single-stage packing, which is a different silencing principle to a chambered design.
Can it be installed backwards?It is reversible, so it can be fitted in either flow direction during a custom installation.
How long is it overall?22 in overall, with an 18 in body between the necks.
Does it come with a tip?No. The outlet is a plain 2.25 in standard style with no tip.
Is a hanger supplied?No, and no gaskets or clamps are supplied either. Everything mounting-related is separate.
What is the body made of?Aluminized steel with an aluminized finish, built with CNC robotic manufacturing.
Is it street legal?Noise limits are set locally. MagnaFlow specifically warns to check local noise regulations before fitting a glasspack.
What warranty applies?A 90-day limited construction warranty, which is much shorter than MagnaFlow's performance system coverage.
Installation Instructions
- Confirm the exhaust is 2.25 in at the point the muffler will go, since both the inlet and the outlet are 2.25 in centred necks.
- Measure the available space: the body needs clearance for a 3.5 in diameter over an 18 in run, with 22 in of total length including the necks.
- Cut the existing pipe square at the chosen location and deburr both ends.
- Dry-fit the muffler, decide the flow direction, and mark the orientation before committing.
- Support the muffler on a stand or a wire while it is positioned, because no hanger is supplied with it.
- Weld or clamp the inlet and outlet joints, and add a hanger at or near the muffler so its weight is not carried by the pipe joints alone.
- Check clearance to the floor pan, fuel and brake lines, and the driveshaft before final welding.
- Run the engine and check the joints for leaks, and confirm the resulting noise level against local regulations.
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