1999-04 Mustang SLP Loudmouth Cat Back Exhaust System Stainless Steel GT 4.6 by SLP

1999-04 Mustang SLP Loudmouth Cat Back Exhaust System Stainless Steel GT 4.6

SLP’s Mustang Loud Mouth cat back exhaust system has always been the best performing catback exhaust in the business. Now it’s the most versatile, too!

Item #SLP-M31007
MPN# M31007

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  • Ford Mustang - 1999, 2000, 2001, 2002, 2003, 2004
  • Sub Models: GT
  • Engines: 4.6
Made in the USA


  • Virtually Zero Flow Restriction
  • Meanest Sound Around
  • Increased Horsepower


  • Modular Design For Easy Muffler Swaps
  • Mandrel Bent 304 Stainless Steel
  • 3.5" Polished Tips
  • 2.5" Diameter

 What's in the Box

  • (2) SLP Loudmouth Resonators With Starter Tubes
  • (2) Tail Pipes
  • (2) 3.5" Polished Stainless Tips
  • All Needed Hardware & Clamps

SLP Loudmouth Cat Back Exhaust System

SLP's Mustang Loud Mouth™ cat back exhaust system has always been the best-performing catback exhaust in the business. Using groundbreaking modular technology, SLP has developed a system that can be quickly reconfigured to fit changing performance, noise level, and sound quality requirements. Simply loosen a few band clamps, swap muffler types, re-tighten, and you're done. No other system offers this level of performance and adaptability! Along with the included resonators, the Mustang SLP Loud Mouth™ catback exhaust system is compatible with SLP's bullet-type Loud Mouth II™ Mufflers (SLP-31064) and their traditional style PowerFlo™ Mufflers (SLP-31065). They both offer flow and performance similar to SLP's resonators but feature a ceramic-wrapped, perforated core that reduces high-frequency noise and in-car resonance for complete control over your Mustang's sound and performance characteristics.

SLP Loud Mouth Resonators

SLP's Loud Mouth™ "Shotgun" resonators offer wide-open exhaust flow and race-ready performance with an ultra-aggressive sound to match. Standard equipment on SLP Loud Mouth™ exhaust systems, each resonator boasts its own unique tone and flow characteristics. They are constructed from hand-polished stainless steel and embossed with the classic SLP logo. NOTES: Includes Loud Mouth™ resonators. Loud Mouth II™ and PowerFlo™ mufflers are sold separately.


  • Includes SLP's infamous Loud Mouth™ resonators for virtually zero flow restriction and the meanest sound around
  • Employs SLP's exclusive modular technology, making it possible to switch between resonator and muffler types in a matter of minutes
  • Dyno-proven to outperform competitive resonator-type exhausts
  • Engineered and built to OEM standards to ensure proper fit
  • Constructed entirely from mandrel-bent 304 stainless steel
  • Features show quality polished resonators and 3.5" double-wall tips with electro marked SLP logo


  • Fits 1999-2004 Ford Mustang 4.6L GT, Bullitt and Mach1

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About This Brand

SLP - Packaged Performance, Guaranteed Horsepower
SLP's Loudmouth exhaust is one of the most recognized systems on the market! They strive to offer the highest quality aftermarket components for Latemodel Mustangs! Their high quality exhaust components increase power, performance, and give your Mustang a louder exhaust tone for that true American muscle car sound. Choose from a variety of cat back, axle back, and resonator kits for your Mustang at
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