Thunder header mufflers
Supporter
Joined: Jul 2007
Posts: 2,196
Likes: 10
From: Shenandoah, TX
When you ask about slip-ons, are you talking about Thundercones or 2 into 1 Thunderheader? Do you have stock headers or true duals? I had true duals and a sit of Thundercones slip-ons, and they sounded great. But after my 98" build, my indy told me I was loseing to much low in torque. He recomended 2 into 1 Thunderheader,WOW he was right. Sounds the same,but oh what tq. Theres not much you can do with the Thundercones or the Thunderheader as for as baffles that I know of. They are what they are. They have a sound of there on,and its good. Don't know if I answerd your ?, but I highly recomend them.
Elite HDF Member
Joined: Nov 2006
Posts: 3,647
Likes: 11
From: Stockbridge, GA (Atlanta)
I am running thundercones on my stockheader system -- if you have stock motor you will not notice much of a difference with the exception of the sound -- you either love or hate the sound. I luv it.
Road Master
Joined: Jul 2008
Posts: 1,142
Likes: 7
From: Michigan
I loved the sound for about the first month, and then i did a 500 mile day, and would have taken them off that night if i had anything there to replace them with. Just too f'n loud, after a full day.
Outstanding HDF Member
Joined: Nov 2005
Posts: 2,408
Likes: 2
From: Houston (Area)
I had thunderheader slipons my stock set up and I just loved the sound! Then I did my HQ build and the sound got even better. Then I went to the fullsac duals and the sound is now in stereo. I know I lost some low end torque but I don't care. When I pull up in a crowd they have no idea if I have low end torque or not, but they sure as hell hear me.
Road Warrior
Joined: Feb 2009
Posts: 1,401
Likes: 4
From: SoCal
got the Thunderheader s/o when I had my '02 FLHR...sounded great at first (but found it to be NOT loud enough later on 
).
).
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Cruiser
Joined: Sep 2008
Posts: 174
Likes: 0
From: Imperial, MO
Had the slip-ons on a 91 FLHTC and they souned great but caused a severe lean problem (acted like it was running out of gas) at 2800 to 3000 RPM when riding 2 up and a steady throttle. Could not get rid of it with tuning or anti-reversion cones so I took them back off and replaced them with some Joker Machine Fishtail slip-ons (don't think they're made anymore) and no more problems.
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Tourer
Joined: Apr 2008
Posts: 309
Likes: 3
From: West Sacramento CA
I ran the two into one set-up for the longest time, did not want to lose the low end with a dual set-up, found a set of dual slip ons and stuck the stock piping on the left side and made a mount to support the left side pipe from any movement, it looks like a bagger now with two pipes coming out the back. you have to look very closely to see the pipe does not connect to the back cylinder. now I have spare slip on I can sell. it has some blueing on it.
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