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ProXS Universal Oval Muffler with Internal X-Pipe
Borla 400493 is a universal ProXS muffler built for custom exhaust work rather than one vehicle. The oval T-304 stainless case measures four inches by nine and a half inches and is nineteen inches long, with two two and a half inch inlets at one end and two two and a quarter inch outlets at the other, giving twenty four inches overall. Inside the case an X-pipe crosses the two paths, which is what gives the ProXS its tone, and the notched necks let the muffler clamp on rather than requiring a weld.
Key Features
- Internal X-Pipe crossover for the ProXS exhaust note and flow
- T-304 stainless steel construction throughout
- Dual two and a half inch inlets with dual two and a quarter inch outlets
- Reversible design, so the case can be turned to suit the routing
- Notched necks for clamp on assembly with one inch wide band clamps
- Universal application for custom exhaust builds on cars, trucks and SUVs
Fitment
| Application | Inlet | Outlet | Requirement |
|---|---|---|---|
| Universal custom exhaust | Dual 2.5 inch | Dual 2.25 inch | Suits systems built around 2.5 inch inlet piping and 2.25 inch tailpipe piping |
This is a universal application part with no year, make or model listing. Compatibility is decided by pipe diameter and the space available for a nineteen inch body with a twenty four inch overall length. One inch wide band clamps, part 18325, are required and are not supplied.
Specifications
| Detail | Value |
|---|---|
| Part number | 400493 |
| Series | ProXS |
| Configuration | Dual inlet, dual outlet |
| Inlet | Two at 2.5 inches |
| Outlet | Two at 2.25 inches |
| Case shape | Oval |
| Case dimensions | 4 inches by 9.5 inches, 19 inch body length |
| Overall length | 24 inches |
| Internal design | X-Pipe crossover |
| Material | T-304 stainless steel |
| Neck style | Notched for clamp on installation |
| Recommended clamps | One inch wide band clamps, part 18325, sold separately |
| Application type | Universal |
| Condition | New |
What's Included
- One ProXS universal oval muffler
About Borla
Borla builds performance exhaust components from T-304 stainless steel and develops its muffler internals around straight through and crossover designs rather than packing that burns out. The ProXS line applies that approach to universal cases so a fabricator can build a full system around a known tone.
FAQ
Is this a bolt on part for a specific vehicle?No. It is a universal case intended for a custom or fabricated system, so the fitment decision comes down to pipe size and available space.
Do the inlet and outlet sizes differ?Yes. The two inlets are two and a half inches and the two outlets are two and a quarter inches, so the tailpipe side steps down slightly.
What does the internal X-Pipe actually do?It crosses the two gas paths inside the case, which balances pressure between the banks and is what gives this muffler its characteristic tone rather than a simple straight through note.
Can the muffler be fitted either way round?The case is reversible, so it can be turned to suit the routing. The inlet and outlet diameters differ, so the pipe sizes decide which end goes where.
Does it need to be welded in?No. The necks are notched for clamp on assembly. One inch wide band clamps are the correct type and are not included.
How much space is needed to fit it?The body is nineteen inches long and the overall length including the necks is twenty four inches, in a case four inches deep and nine and a half inches wide.
Why stainless steel rather than aluminised steel?T-304 resists the salt and condensation that rot a plated case from the inside, which is what usually ends the life of a cheaper muffler.
Will it be loud on a street car?The ProXS design is aimed at an aggressive tone rather than a quiet one. Pipe diameter, system length and the presence of a resonator all change the result on a given vehicle.
Is any hardware supplied?The muffler is supplied on its own. Clamps, hangers and connecting pipe are part of the system build.
Installation Instructions
- Plan the exhaust routing and confirm there is clearance for a twenty four inch overall length before cutting anything.
- Support the vehicle safely on stands and allow the exhaust to cool completely.
- Position the muffler with the two and a half inch necks toward the engine and the two and a quarter inch necks toward the rear.
- Slide the inlet pipes into the notched necks to the depth the notches allow.
- Fit one inch wide band clamps over each neck without tightening them yet.
- Check the muffler sits level and clear of the floor, heat shields, driveshaft and any fuel or brake line.
- Set the hangers so the weight of the case is carried by the mounts rather than the clamped joints.
- Tighten each band clamp evenly, then run the engine and check every joint for leaks before road use.
Prop 65 Warning
This product can expose you to chemicals which are known to the State of California to cause cancer or reproductive harm. For more information go to www.P65Warnings.ca.gov.
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