Borla Universal Pro-XS Transverse Flow Single 3-Inch Inlet / Dual 2.5-Inch Outlet Polished T-304 Stainless Steel Oval Muffler with Notched Necks (400499)
Unlock ultimate exhaust flow and aggressive acoustic tuning with the Borla Universal Pro-XS Transverse Flow Specialty Muffler. Masterfully engineered to meet the unique structural requirements of GM F-Body vehicles, custom high-flow split-rear conversions, and space-constrained street builds, this high-efficiency unit utilizes a specialized single 3-inch offset inlet and dual 2.5-inch offset outlet port routing layout. This advanced architecture houses the 3-inch primary inlet and one 2.5-inch outlet on one end cap face, while the second 2.5-inch outlet exits the opposite end cap face. At its mechanical core, this premium performance muffler breaks away from restrictive traditional baffle layouts by incorporating Borla’s cutting-edge straight-through internal geometry adapted for transverse routing. This innovative layout features a high-velocity perforation core that optimizes gas flow and exhaust velocity, generating an excellent scavenger effect. This advanced aerodynamic design maximizes peak horsepower, expands torque delivery, and completely eliminates backpressure bottlenecks for optimized performance configurations.
The structural engineering of the Borla 400499 addresses long-term durability and installation problems beneath harsh track and street conditions through a 100% welded, heavy-gauge setup. Enclosed in a robust 6-inch by 10.25-inch oval by 19-inch long barrel case with a total 24-inch overall footprint, this specialized assembly delivers excellent space optimization when mounted crosswise behind the rear axle, tucked neatly beneath the rear bumper valance, or fitted into tight under-car layouts where traditional longitudinal mufflers cannot go. The specialized straight-through internal routing packs a massive volume of advanced, high-temperature Continuous-Filament Fiber (CFF) acoustic sound control packing. This advanced insulation filters out high-frequency rasp and annoying highway cabin drone while preserving a raw, unrestrictive mechanical tone under full throttle. Built completely from aircraft-quality, premium-grade T-304 austenitic stainless steel finished in a natural mill texture with convenient notched neck bases, this heavy-duty canister accommodates custom brush or mirror-polished workshop textures prior to installation. Capable of being flipped or reverse-mounted due to its completely uniform, reversible internal configuration, this elite USA-made performance component delivers bulletproof structural stability backed by Borla’s legendary Million-Mile warranty.
Straight-Through Flow Dynamics & Space Optimization: Unlike basic factory replacements or restrictive multi-chambered mufflers that choke engine velocity, this Pro-XS unit features a high-flow cross-flow network. Originally engineered to run parallel to the rear axle on high-performance Chevrolet Camaros and Pontiac Firebirds, this transverse flow configuration allows custom builders to route a large 3-inch mid-pipe into a balanced dual 2.5-inch exit exhaust system without forcing the exhaust gases through restrictive 90-degree internal chamber turns or baffle plates.
Fabrication Installation Guideline Note: This high-performance universal muffler is built with factory notched attachment necks engineered explicitly for clean, hassle-free clamp-on installation utilizing standard 1-inch wide band style clamps (clamps not included; use Borla clamp part numbers 18330 for the 3" inlet and 18325 for the 2.5" outlets, or standard 3" wide clamps 18006 and 18004). If your project demands smooth, un-notched connection collars for a permanent weld-on workshop connection instead of a slip-fit clamp joint, see alternate part number 40474.
Features
- High-Flow 3-Inch to Dual 2.5-Inch Transverse Core: Replaces restrictive baffled internal designs with a specialized high-velocity cross-flow path to maximize horsepower and dual-tip exhaust velocity
- Specialty F-Body Transverse Layout: Symmetrical single inlet and dual outlet layout fits perfectly behind the rear axle line, running parallel to the chassis frame rail
- High-Capacity 3" Primary Inlet: Step-up 3-inch inlet neck accommodates higher volume exhaust gasses from upgraded mid-pipes and high-horsepower systems
- Unique Tri-Port End Configurations: Positions the main 3" inlet and first 2.5" outlet on one end cap base, with the secondary 2.5" outlet placed on the opposite end cap face
- Premium Continuous-Filament Fiber: Packed with high-temp CFF insulation to absorb harsh frequencies and maintain a deep, sporty tone under load
- Factory Notched Connection Necks: Specially pre-slit for fast, secure clamp-in installation with standard 1" wide band style hardware
- 100% Symmetrical Reversible Layout: Bidirectional configuration provides ultimate fabrication flexibility, allowing it to be installed in either direction
- Heavy-Duty 100% Welded Body: Fully welded seams deliver maximum structural strength to resist extreme backfire pressures and track vibrations
- Constructed completely from premium-grade T-304 austenitic stainless steel for permanent structural integrity and ultimate rust resistance over low-grade 400-series hardware options
- Proudly Manufactured in the USA: Built in America by the world’s most experienced exhaust brand to guarantee flawless fitment and elite race-proven quality
Detailed Fitment Breakdown
Universal Application Parameters & Structural Boundaries:
This premium universal Pro-XS performance transverse muffler with notched necks is compatible with a massive array of custom and production vehicle platforms under the specific architectural parameters detailed below:
Universal Automotive & Custom Exhaust Fabrication Fitment:
- Directly ideal for GM F-Body vehicle configurations including upgraded Chevrolet Camaro and Pontiac Firebird platforms utilizing a crosswise muffler position
- Integrates seamlessly into custom fabrication builds requiring a single 3-inch mid-pipe feed that splits into independent left-and-right dual 2.5-inch rear exit tailpipes
- Highly recommended for vehicle configurations requiring a space-conscious transverse layout behind the rear differential assembly to maximize ground clearance
- Compatible across all domestic and import car, truck, and SUV platforms with sufficient clearance for a 6" x 10.25" oval body footprint
Sizing, Connection & Dimensional Details:
Fits your project layout across these exact structural specifications:
- Inlet Connection Size: Single 3.00-Inch internal diameter offset port neck
- Outlet Connection Size: Dual 2.50-Inch internal diameter offset port necks
- Muffler Case Configuration: 6.00-Inch x 10.25-Inch specialized cross-flow oval structural shape
- Muffler Case Body Length: 19.00 Inches of primary sound suppression coverage
- Overall Muffler Total Length: 24.00 Inches from inlet tip to outlet tip boundary
- Internal Architecture Matrix: Straight-through transverse high-flow performance configuration with premium CFF sound material
- Material Grade Composition: Authentic T-304 Austenitic Stainless Steel with a natural mill finish
Important Application Notes:
- **Premium Materials:** Built entirely with authentic T-304 stainless steel to deliver superior rust resistance and durability over lower-grade T-400 series or aluminized hardware choices.
- **Versatile Fabrication Paths:** Engineered as a professional universal component with notched slip-fit necks, providing custom fabricators with a dependable, heavy-walled material block that can be easily clamped or welded if desired.
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