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2 into 1 High Performance Exhaust System - 1031

  • Part #:
    4400340
  • Mfg Part #:
    1031
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2 into 1 High Performance Exhaust System - 1031

  • Part #:
    4400340
  • Mfg Part #:
    1031
MSRP: $845.00

Price: $671.38 21% off!
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Thunderheader 2 into 1 High Performance Exhaust System - 1031
  • New design for 2020 accommodates both 12mm and 18mm O2 sensors with the included 18-12mm reducers for expanded fitments 
  • New 1039 manufacturer's number replaces old 1031 and 1035
  • Designed to give maximum horsepower without sacrificing low-end torque
  • 2-into-1 systems with patented collector design that directs spent exhaust gases in a spiral motion through four acoustical dampening chambers
  • Exhaust travels through these chambers at high velocity to scavenge spent exhaust gases from the combustion chamber and bring in a fresh charge of air/fuel mixture
  • Anti-reversion design works to impede reverse flow through the system -- reverse flow can contaminate the incoming fuel/air mixture, which reduces performance and throttle response
  • As reverse flow enters the collector, the diffuser deflects it through vents; the pyramidal trap and apertures impede the reverse flow, allowing time for the exhaust valve to close
  • Flow director has equal area at each end, allowing exhaust gases to travel at a constant velocity over the entire length to improve exhaust scavenging
  • For heat shields, order the following:
    14 in. Top Front - H25-035
    23 in. Top Rear: H25-034
    13-1/2 in. Collector - H25-029

Included Items:
(1) Exhaust header
(2) 18mm to 12mm Port reducers
(1) 5/16-18 x 1-1/4 in. Hex bolt
(4) 5/16 in. Plain washers
(3) 5/16 in. Lock washers
(3) 5/16-18 Nuts
(1) 3/4 in. Clamp
(2) 5/16-18 x 3/4 in. Hex bolts
(1) Mounting bracket



Not all products are legal for sale or use on pollution controlled vehicles. Check your local laws and the manufacturers information

There is no warranty on exhaust pipes and mufflers with regard to any discoloration. Discoloration (bluing) is the result of tuning characteristics, cam timing, carburetor jetting, overheating, etc., and is not caused by defective manufacturing. See the CHEMS/LUBES section for products that will help prevent or remove bluing.

Installation of a new exhaust system may change your motorcycles fuel-air mixture requirements. Please consult the exhaust manufacturer directly with questions regarding any modifications that may need to be made during, or after, installing their product. If a jet kit or fuel processor is recommended, see the FUEL/INTAKE section



The Air Resources Board (ARB) does not permit the use of aftermarket emission-related parts that alter the air/fuel ratio of an emission-controlled vehicle. Due to these legal restrictions this part cannot be shipped to California.

Specifications
Part #: 4400340
Mfg #: 1031
Color Chrome
Finish Chrome
Style Tapered Tip
Type 2-Into-1 System
Units Each
Weight 22.18 lbs
WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov
Resources & Manuals
Fitment for Thunderheader 2 into 1 High Performance Exhaust System - 1031

Part 4400340 fits the following machines

Harley-Davidson
  • Dyna Fat Bob - FXDF 2009-2011
  • Dyna Fat Bob (EFI) - FXDF 2008
  • Dyna Low Rider - FXDL 2009
  • Dyna Low Rider (EFI) -FXDL 2007-2008
  • Dyna Low Rider Injected - FXDL I 2006
  • Dyna Street Bob - FXDB 2009-2011
  • Dyna Street Bob (EFI) - FXDB 2007-2008
  • Dyna Super Glide - FXD 2009-2010
  • Dyna Super Glide (EFI) - FXD 2007-2008
  • Dyna Super Glide Custom - FXDC 2009-2011
  • Dyna Super Glide Custom (EFI) - FXDC 2007-2008
  • Dyna Super Glide Custom Injected - FXDC I 2006
  • Dyna Super Glide Injected - FXD I 2006
  • Dyna Wide Glide - FXDWG 2010-2011
  • Dyna Wide Glide (EFI) - FXDWG 2007-2008
  • Dyna Wide Glide Injected - FXDWG I 2006
  • Street Bob Injected - FXDB I 2006

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Reviews & Questions
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Browse 9 questions Browse 9 questions and 10 answers
Does this have heat shields?
A shopper on Nov 30, 2016
BEST ANSWER: Love it
I know it'll for my 06 fxdli but will it work with floorboards?
Jake H on Dec 17, 2019
BEST ANSWER: Yes it should
will it fit a 1995 springer that has a 111 S&S with saddle bags?
A shopper on Dec 14, 2019
BEST ANSWER: No, see fitment tab for correct fits
Does this price include heat shields?
A shopper on Apr 27, 2019
BEST ANSWER: No
Will this fit my 2008 fatbob?
A shopper on Apr 23, 2019
BEST ANSWER: Yes, see fitment tab for correct fits
This model + shopping to Singapore?
A shopper on Aug 14, 2018
BEST ANSWER: To find shipping charges, you may place your order online at www.denniskirk.com Once you have entered your shipping address, you will see your shipping options along with the charges before you complete your order. Or you can call our sales staff (800-969-7501) and they can let you know the shipping charges
Will it fit with floorboards?
A shopper on Jun 29, 2018
BEST ANSWER: Yes
Are California legal?
A shopper on Mar 2, 2018
BEST ANSWER: The Air Resources Board (ARB) does not permit the use of aftermarket emission-related parts that alter the air/fuel ratio of an emission-controlled vehicle. Due to these legal restrictions this part cannot be shipped to California.
Will this fit a 2007 fxdse?
A shopper on Apr 6, 2017
BEST ANSWER: yes
4.5 / 5.0
16 Reviews
5 Stars
4 Stars
3 Stars
2 Stars
1 Star
11
4
0
0
1
Finish
4.8 / 5
Fit
5.0 / 5
Performance
4.9 / 5
Styling
5.0 / 5
Value
5.0 / 5
Loudness
Very Quiet
Average
Very Loud
Would you recommend this product?
Yes (4)
Finish
5 / 5
Performance
5 / 5
The right pipe-apology long review
The right sound, easy to install, 10HP, 20FtLbs Torque bolt-on. Get the shield kit or cook your leg.
Yes it's a bit louder than VH duals. But a deeper, respectful, commanding duntDunt. Not the obnoxious blatBlat from the BigRadius 2-1.
So I got a free Dynotune from a dealer, who dyno'd it the next week with only this $650 mod (with shields). From 94HP/104# torque to 104hp/124#torque.
Provides the performance I needed from stock on my '09 FXDFSE. Dynotune is a must from stock-it turned my skoot to a monster.
Buy 2 rear tires, cause they won't last.
Comes with O2 ports, perfect fitment, mounting bracket and all you need minus the head port gasket (why not? -it's right there and $5 pair).
25 mins to install, no fancy tools except a swivel socket extension. And ale-pale Ale.
January 28, 2014
Finish
4 / 5
Performance
5 / 5
instant horsepower
best addition to my motor yet..horsepower increase you can feel in the seat of your pants ...product was expertly packaged and arrived in perfect condition .....
January 18, 2011
Finish
5 / 5
Fit
5 / 5
Loudness
Very Quiet
Average
Very Loud
Performance
5 / 5
Styling
5 / 5
Value
5 / 5
Would you recommend this product?
Yes
Only the best
Had one Thunderheader before loved it so much I got another
December 6, 2016
Purchased
over 3 years ago
Finish
4 / 5
Performance
5 / 5
No Review Title Entered By User
Need longer bolts to mount bracket to transmission
Tight fit between pipe and foot-board - slotted hole would be helpful
January 19, 2011
Mpls, MN
Finish
5 / 5
Performance
5 / 5
Great addition
I recently purchased a 2001 Dyna Low rider with 7000 miles from a great previous owner that did very little to the bike but maintain it. He did put a Mikuni carb on it. My plan was to do the bike up right and quick..two weeks...but tasteful. I added the intake and cleaner and quite a few other items to dress the bike up to my style. Most importantly I waited until last to do the exhaust, so I called Mikuni and talked to Steve...told him what I was doing and asked for his advice. Afterwards, given my style I was going for and the performance I was seeking, he offered the Thunderheader as a choice. He explained that since I lowered the bike and wanted performance, this was a good choice. I forgot to mention, this is my first bike, and I did all the work and upgrading myself. This pipe couldn't have fit better and easier. Awesome piece of equipment!
July 11, 2013
Pittsburgh, PA
Finish
4 / 5
Performance
5 / 5
wanna make your bike sound like a drag bike?
very good investment for the price. It is only loud when you really twist the wick. Really increased the torque curve.At 65 or above you will really feel the push all the way up to where you think you are going to take off.At 120 you still can feel the torque pushing you back.
January 25, 2012
Finish
5 / 5
Performance
5 / 5
Thunderheader Exhaust
Love the way this exhaust sounds on my fatboy. My husband has one on his roadking and we are very impressed!
January 6, 2012
Finish
5 / 5
Performance
5 / 5
No Review Title Entered By User
No Review Text Entered By User
May 18, 2010
Finish
5 / 5
Performance
4 / 5
No Review Title Entered By User
One of the easiest pipes I've installed. (and I've installed many) It has that one and only thunderheader sound. Very good finish, I would recommend to others.
February 28, 2012
Finish
5 / 5
Performance
5 / 5
Rumble
Just what I had heard, great sound and looks great. Fast shipping and great communication
December 5, 2015
Fairfield, CA