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Exhaust› Exhaust Pipes, Systems and Components

Flo Pro

5-Inch Downpipe-Back Exhaust System

Name: 5-Inch Downpipe-Back Exhaust System
Brand: Flo Pro
SKU: 680NM

$710.00 $485.00 Save $225.00

SKU: 680NM

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Overview

The Flo Pro 680NM is a 5-inch downpipe-back exhaust system designed for 2017-2019 L5P 6.6L Duramax trucks. This system is constructed from durable stainless steel and features straight-pipe, no-muffler design. It replaces all stock components, including clamps, pre-welded contour hangers, and reinforced flanges for installation.

Show original supplier description

The Flo Pro 680NM is a 5-inch downpipe-back exhaust system specifically engineered for 2017-2019 L5P 6.6L Duramax Chevrolet and GMC trucks. The 5-inch piping is intended to improve torque, enhance exhaust flow, lower Exhaust Gas Temperatures (EGTs), and potentially improve fuel mileage. **Important Fitment and Installation Notes:** * This kit is compatible with all wheelbase and cab configurations for the specified years and engine, provided the vehicle is equipped with the OEM-style 4-bolt flange off the turbo direct pipe. It is not compatible with models using a 3-bolt flange. * A custom delete tune is required for your L5P to prevent the ECU from searching for the missing Diesel Particulate Filter (DPF) and DEF systems, which could otherwise lead to error codes or limp mode. * For tuning, HP Tuners with CCS Tuning and an unlocked ECM are recommended. * This system is not compatible with a 2021 GMC crew cab 4WD. It is, however, compatible with a 2020 crew cab and all bed and cab configurations for the 2017-2019 L5P models.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

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Specifications

Brand	Flo Pro
Part Number	680NM
Category	Exhaust

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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

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