DK Custom Products

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Thunder Torque Inserts 158 For Increased HP & Torque

Availability: In stock
Item #: DK-TTI-158
Manufacturer: DK Custom Products

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 DK Custom Thunder Torque Inserts Increase Torque & give Flexibility in sound volume increasing inertial scavenging reducing engine pumping losses, increasing exhaust gas velocity Harley Davidson


Increases Low & Mid Range Torque

Adjustable Sound Volume & Tone

For Your

Slip-on Mufflers & Full Exhaust Systems

 MADE in The USA!


DK Custom Products


  • High-Temp Powder Coat Finish
  • Stainless Steel Studs (5/16" diameter)
  • Includes All Hardware
  • FITS 2" diameter & larger Slip-ons (other sizes available)
  • Increases Low & Mid Range Torque
  • Increased Exhaust Gas Velocity
  • Increased Inertial Scavenging
  • Adjustable Sound Volume & Tone
  • Option for only 1 TTI for 2-1 exhaust systems
  • E-Z Installation  Bolts into the end of the slip-on muffler (using the baffle bolt hole)
  • Patented Technology
  • Made in The USA!

Watch these videos on how to get a better sound AND increase torque!

Take a listen to the following sound clips of 5 Different Bikes that all have an increased amount of Power from Thunder Torque Inserts™ Being Installed.


***The Video Below shows how to Remove Baffles from stock OEM Mufflers that do NOT have a Catalytic Converter in them.  This process does NOT work on Mufflers that have Catalytic Converters in them.***


Do you want Louder Exhaust? 

Quieter Exhaust? 

A Deeper Tone? 

A More Aggressive Bark? 

Do you want More Torque?


The Video Below shows how to Remove Baffles from stock OEM Mufflers that DO have a Catalytic Converter in them. 


Another Video showing how good the stock exhaust can sound, and how much power they can have, with the baffles removed and replaced by Thunder Torque Inserts™.


All the Vance & Hines Systems and Slip-ons we've tested produce more power, and a bit deeper tone with TTI's Installed.  The V&H's respond particularly well to TTI's, with or without the baffles!


Without getting too technical, we've spent thousands of hours testing shape, size, thickness, & surface coatings to find the optimum combination that increases power across a wide RPM band, AND gives maximun flexibility to deliver different sounds.

The Increase in Torque is accomplished by reducing engine pumping losses, increasing exhaust gas velocity and increasing inertial scavenging.

Thunder Torque Inserts™ are designed to perform well when used on slip-ons with and without baffles, drag pipes, shortys and 2-1 Systems. 

The Patented design will produce a bit deeper sound/rumble all the way through the RPM and Throttle range. 


When ordering you have an option of getting just ONE TTI if you have a 2-1 exhaust system that has only One slip-on, or to choose TWO TTI's for exhausts that have Two Slip-ons.

The "Q" model is no longer being manufactured.

Click this LINK to see Pictures & Fitment Information, to Choose the Correct Size for your Exhaust


 A small change can make a BIG Difference!!!



 Check out the Dyno Charts Above!


"We just installed the Thunder Torque Inserts. The change is very noticeable.   ..using Screaming Eagle II Slipons without baffles.   Metallic sound disappeared with the inserts!

...always a drop in power from 2,700 to 3,200 RPMS in any gear.   Now the power delivery is very linear and smooth in the whole powerband.


It's amazing to feel that something so small, simple and easy to install made so much difference on the bike !!


Thanks so much for all!!!" -Concha



"Just wanted to take a minute and let you guys know how pleased I am with the W258 TTIs.


I'll be honest, when I first read about these things I figured it was somewhat gimicky so I didn't expect much. But, after removing the baffles from my Wild Pig slip ons and installing the W258's I was blown away by both sound and performance!


It has the potato potato sound at idle (noticeably louder than before) and also sounds great at cruising RPMs. It actually reminds me of the way my old shovel head sounded.


What really surprised me though was the very nice torque gain that you can really feel. After installing true duels and the wild pigs, I noticed a loss in torque. The TTIs brought all of that back, and maybe then some!


Best money I've spent on my exhaust system for sure. Thanks!" -Dewayne





Customer Reviews

TTi 158s in upswept fishtails Review by Bob
Installed Paughco upswept fishtsils on my 48. They are one piece pipes w/o baffles. Very loud and the bike would hardly run. No low end torque at all.
Modified the 158s (ovalized) to fit and installed and adjusted. Now the pipes sound like upswept fishtails should and the low end is back. These inserts are the best. (Posted on 12/17/2017)
Great!! No more popping when deccelerating Review by YeyO
Amazing! These little budies seem inofensive, they seem so simple...but once installed in my FXDC they really, really do their job! I was really struggling with FI due to a lot of decceleration explosions (V&H Twins Slash slipons w/o baffles). The TTI not only eliminated Completely the popping, my bike now has a lower deeper tone, no more metallic sound and recovered a lot of torque in the lows. (Posted on 11/11/2017)
Best money I've ever spent. Review by Brad
I put the W158's on my '02 Shadow VT1100 in about 30 minutes (had to drill holes), and I IMMEDIATELY felt a difference. The previous owner had taken a holesaw to the baffles and I've been trying to get the engine dialed in since I bought it. The bike sounds a lot better, it got rid of the hollow, twangy, metallic sound and now has a deep, warm grumble. I can feel a HUGE difference in torque all the way up the rev range and I actually get pushed into the seat now. All in all these are a great buy. (Posted on 8/27/2017)

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