Exhaust Kit for Chevrolet Silverado (1998-1999) 5.7L

High-Flow Dual Muffler-Back Exhaust Kit for 1998-1999 Chevrolet Silverado (GMT400)

What it Does: The dual muffler-back exhaust kit replaces the restrictive factory single muffler and tailpipe assembly on the 1998-1999 Silverado to evacuate exhaust gases faster, reduce parasitic backpressure, and improve low-end towing torque.

The Stock Chevrolet Silverado Exhaust Restriction

The OEM exhaust routing on the GMT400 platform utilizes a heavy, baffled single-inlet muffler paired with restrictive crush-bent tubing. These factory bends narrow significantly at radius turns, disrupting exhaust gas velocity and trapping thermal energy near the rear axle. Under heavy load or sustained towing, the stock chambered configuration restricts volumetric efficiency on the Vortec 5700 L31 small block, causing unnecessary exhaust gas recirculation in the cylinders, sluggish throttle response, and muted acoustics.

The Engineering Solution

This kit resolves upstream bottlenecks using a two-chambered Flowmaster Super 44 muffler featuring a single 3.0-inch inlet and dual 2.5-inch outlets to maximize scavenging dynamics. Fabricated from corrosion-resistant aluminized steel, the dual 2.5-inch tailpipes utilize smooth, CNC mandrel-bent routing that maintains cross-sectional diameter through every contour. The pipes route cleanly along the outside of the frame rails, engineered specifically with drop clearances for the factory spare tire and OEM receiver hitch while supporting all bed and cab wheelbases.

What's Included

• 1 Flowmaster Super 44 muffler (single 3" inlet, dual 2.5" outlets)
• 2 aluminized mandrel-bent multi-piece 2.5" tail pipes (slip-together)
• 8 muffler clamps
• 1 larger exhaust clamp
• 4 rubber-insulated hangers

Technical Specifications

Compatibility

• 1998 Chevrolet Silverado C/K 1500 / 2500 / 3500 (5.7L V8 Gas, Single Inlet Muffler)
• 1999 Chevrolet Silverado 1500 / 2500 / 3500 Classic (5.7L V8 Gas, Single Inlet Muffler)

Frequently Asked Questions & Fitment Warnings

Does this fit the GMT400 Silverado?

Yes, this is a direct fit for the 1998-1999 Chevrolet Silverado equipped with the Vortec 5700 L31 5.7L gasoline engine. This kit exclusively fits trucks equipped from the factory with a single-inlet muffler; it will not fit dual-inlet factory setups or models with aftermarket modified chassis configurations.

Is this exhaust system a direct bolt-on installation?

No, this is a universal-fit muffler-back kit that requires an experienced installer or exhaust technician to trim or fabricate intermediate pipe connections forward of the muffler.

The Chevrolet Heavy-Duty Caliber

Engineered to handle severe duty cycles, this system ensures your GMT400 retains the thermal durability and backpressure profile required for sustained towing, rough farm transit, and heavy payload demands without fracturing factory hanger brackets.