There are too many posts, with too many opinions for me to take the time to address each one individually.


Here are some relevant facts:

We do not sell anything that we do not test, get good results, and use on our own bikes. We do not have "marketing" material to make things look better than they are.

We've tested hundreds of ideas/items, and if they are no good they get ****-canned. If they are good, we put them up for sale and publish the results.


There are thousands of TTI's installed on bikes every year, for almost a decade now. We've seen less than a dozen pipes experience cracks. Those that did were either old pipes (that were rusting out), pipes with the holes drilled Not per the instructions, or installed, Not per the instructions.

Is it possible a crack could develop? It is Extremely unlikely if directions are followed.


I am not going to get in protracted conversations on the following subject, but will say this.

One of the strongest myths regarding Harley's is: They need back-pressure to run well.

This back-pressure myth is too strong for me to spend time fighting it.

Please do not take offense, nor think I am backing down from my statement if I do not respond, taking the time to engage in conversation on the subject.

I'll simply state:

Back-pressure fights AGAINST performance. Back-pressure holds back power, not unlike a 300 lb. rider will reduce acceleration more than a 150 lb. rider.

The reason some folks think that back pressure is good, is because when they put a baffle in (which creates back-pressure) the bike runs stronger. BUT, it is NOT running stronger because of the back-pressure, it is running stronger in spite of the back-pressure, because it is reducing Reversion.

It is wrongly assumed that the back-pressure that baffles create increases power. It is the reduction in reversion from baffles that increase power.

The baffle is reducing power because of the back-pressure, but it is increasing power by Reversion reduction. In most cases the power gained by reduction of reversion is More than the power lost to back pressure, so there is a net gain of more power.

But it is IN SPITE of back pressure, not because of it.

What would be best is if there could be a reduction of reversion WITHOUT an increase in back pressure.

That is what we spent countless hours working on many years ago, prototyping dozens and dozens of designs, all in an effort to reduce reversion without increasing back-pressure.

The best we came up with was the "Wavy" Thunder Torque Inserts. So called because of the wave shape they have. These are Patented due to many unique features.

The bottom line is that they do very little to increase back-pressure, and in fact, speed up exhaust gas velocity because of the unique shape. At the same time they reduce reversion.

This is the key to more power...as little back-pressure as possible, and as much reduction in reversion as possible.


There are a couple of "drawbacks" to the TTI's.

1. When installed in concert with factory type baffles, they do little or nothing to increase power. When installed with V&H type baffles (that you can see straight thru, there is a benefit)

2. Since they don't work well with quieter baffles, the exhaust note with TTI's is louder than some folks like.


We have tested TTI's in dozens of different exhaust configurations, and we've only found one type of exhaust that works better without TTI's than with. That is the disc type muffler (like the Fuel Moto E-Series or SuperTrapp).

Every other exhaust, that either has the baffle removed, or has a see-thru baffle, will produce more low & mid range power with the TTI than without.

If anyone ever does back to back tests with the only difference being removal of the baffle (or leave it in for see-thru baffles) and installation of the correct size TTI, and does not see an improvement in low & mid range power, please contact me directly...we've not seen it and I would be very curious of what set-up it was.

And if such a set-up exists, we'll let everyone know, just like we do on the disc type exhaust.

 

Nicely said Kevin! I don't know much about all of what you stated but I do know that your TTI's definitely made a very noticable difference in the performance of my bike when I was running them. I also know that I will be following your instructions to the T this time and will report back on the results over time.

The only thing is I will have to drill a new hole (3/8" this time) since the hole for the baffle fastener is in a not so preferable spot. Also I don't want to drill through the heat shields as well as the pipes to install them and I want the nut in a somewhat hidden location. Thanks for the info and setting the record straight for everyone.

 

Words of the day...

1) Ubiquitous

2) Panacea

 

A couple of years back American Iron Magazine did a test on an old shade tree mechanics trick of installing a bolt through straight pipes to increase torque.

Their dyno tests proved that it did work.

 

Thanks Kevin for taking time to address the OP's concerns. You guys are top notch in parts and service. As a machinist, I stand by my original reply. Take the time to drill a nice, clean hole of the proper size and debur after and you will lessen the chance of cracks. Most baffles are held in place with a bolt and you dont hear about cracks around those holes.

 

As I noted before, I didn't say that there is no benefit in using them. In fact, there's no question that they can have a positive effect. The question is how well they work in different use cases. And in any particular case, do they offer enough benefit to be worth the while? How would one know? The only way to truly know what impact they have in any one particular case, is to do before and after comparisons on a dyno.

In the OP's case, I questioned whether the benefit - assuming there is any in his particular use case - would be significant enough to be worth drilling holes in a set of Rush slip-ons. If those Rush slip-ons in question are the same as those tested over at Hammers website, then they would likely have a pretty decent torque curve - showing little issue with reversion. How would one know if the difference obtained by using TTI's would be worth while - or even positive? Anybody seen any before and after dyno's with Rush slip-ons and TTI's?

I suspect that the benefit of their use in some cases may not be worth the trouble (particularly on a well designed/performing system) and that its possible in some instances that their use could be a net negative. If I were to consider using them, I'd want to see some dyno results - on the particular setup I intended to use them on - to ascertain exactly what impact they have.

Certainly you may see many accounts were folks swear by them. But, impressions from their "butt dynos" are meaningless.

I reiterate the "Words of the day".

 

Since my post in the "what did you do to your sportster today" thread was related to this topic, I figured I would post the link in this thread.

To sum it up, Rush 3" mufflers with 1-3/4" baffles performed significantly better than the Straight shots with only baffles as well as with no baffles and TTI's installed. I didn't try the Straight Shots with baffles and TTI's because the size of TTI's I have are too large to run with the baffles in. Read post 7290 for more details. https://www.hdforums.com/forum/sport...today-729.html

So with that being said, I'm not sure if there is any more to gain outta the Rush pipes by adding TTI's but I'm not going to attempt it. I am extremely happy with how the bike is running with these pipes the way they are. It is super responsive to the slightest twist of the throttle and pulls hard all the way through to the rev limiter. Great pipes overall that need no modification.

 

Wrote up a report on Harley Exhaust- How It Works, Myths and Facts...

It can be seen at this LINK

Here's an excerpted image from it-




Kevin

 

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