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USD 154.99
Part #: MBGMS9421

MBRP GMS9421 4" XP Series Front Pipe

2006-2007 GM 6.6L Duramax LLY/LBZ
Part #: MBGMS9421
★★★★★ ★★★★★ 2 Reviews
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The MBRP GMS9421 4" XP Series Front Pipe is constructred from T409 stainless steel and is designed for use on your 2006-2007 GM 6.6L Duramax LBZ. Designed for use with 4" exhaust systems. 

  • 4" Front Pipe
  • Mandrel Bent & Jig Manufactured 
  • T409 Stainless Steel Construction
  • Lifetime Warranty 


  • MFG. Number GMS9421
  • Manufacturer Name MBRP Inc.
  • Shipping Weight 25.00 lb.
  • Shipping Length 65 in.
  • Shipping Width 12 in.
  • Shipping Height 10 in.
  • Fuel Type Diesel
  • UPC 882963100665
  • Warranty Yes
  • Warranty Info Lifetime
  • Prop 65 WARNING: Cancer & Reproductive Harm -


★★★★★ ★★★★★
5.0/5 Stars out of 2 Reviews
Front Pipe Addition
(Unknown) | May 2nd, 2008
I just got done installing the front-pipe into the exhaust system. I was able to modify it a little to fit the Banks Cat-Back system. Immediately I noticed the faster spool up time and the increase in power. However, the best noticeable increase was in the fuel economy. I had a PPE tuner, Banks intake, and Banks Cat-Back and was getting 16.8 mpg. Now with the addition of the front-pipe, I am averaging 21.1 mpg!!! Definitely the best upgrade to buy for the price! I recommend this to all diesel truck drivers.
Nice Sound
(Midwest) | October 5th, 2008
Once i got the cat cut off it was easy 2 install. Took about an hour. Truck is alot louder and the turbo spools alot faster. Sounds good

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Most Popular Questions

What size is the pipe?
View Staff Answer 
the MBRP GMS9421 4" XP Series Front Pipe is a 4". It's intended for use with aftermarket exhaust systems because it has a flared end, to slip over other aftermarket 4" exhaust systems. Give our Diesel Experts a call at 1-888-343-7354 so we can assist you with building your custom exhaust.
Emissions Notice

This product is not legal for sale or street use in California. Certain aftermarket products are subject to governmental emission standards regulated by the California Air Resources Board. In order for these products to be legal on a specific vehicle in California, the part number must receive a CARB Executive Order (EO) number. This number makes the part legal for use only on specific years, makes and models of vehicles. A decal with CARB EO number for these parts must be displayed in the engine bay to satisfy smog inspection requirements.