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Exhaust› Exhaust Pipes, Systems and Components

Stillen

Cat-Back Exhaust System

$1,720.73 $1,517.88 Save $202.85

SKU: 504377

Special Order
Free Shipping over $200
$100 Minimum Order
Non-Returnable Item
INSTALL DIFFICULTY
DIY PRO SHOP

Moderate — 2–4 hours

Overview

The Stillen 504377 is a cat-back exhaust system designed for the 2009-2013 Infiniti G37 Sedan and the 2015 Q40. It features a dual split rear exit with polished 304 stainless steel dual wall tips. This system is constructed from 304 stainless steel and is mandrel-bent for durability.

The exhaust provides a noticeable increase in horsepower and torque, with a sound profile that is mild at idle, aggressive under throttle, and suitable for highway cruising. It is compatible with both RWD and AWD models.
Show original supplier description
The Stillen 504377 is a premium cat-back exhaust system engineered to enhance the performance and sound of your 2009-2013 Infiniti G37 Sedan or 2015 Q40. It features a dual split rear exit configuration, complemented by polished 304SS dual wall tips that deliver an aggressive aesthetic. The design focuses on improving airflow to unlock substantial horsepower and torque gains, verified by dyno testing for a significant increase at the wheels. Users can expect an authoritative tone under throttle, while maintaining a more luxurious and quiet cabin feel during idle and cruising. Installation is described as straightforward, with the new system fitting together well.
Vehicle Symptoms
  • Factory exhaust sounds too quiet
  • Noticing lack of power in mid-range
  • Wanting a more aggressive exhaust note
  • Looking for dyno-proven horsepower gains
Relevant Conversations
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  • Stillen cat-back exhaust dyno results

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

BrandStillen
Part Number504377
CategoryExhaust
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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.

Free shipping over $200 in the continental US. Alaska, Hawaii, U.S. territories (Puerto Rico, U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands), and international orders carry surcharges — most appear at checkout. Some exceptions (LTL freight, or suppliers who quote freight only after we place the order) won’t. In those cases we’ll reach out with the exact charge before your order moves forward.

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