Why "true duals"
Outstanding HDF Member
Joined: Jan 2007
Posts: 2,598
Likes: 19
From: Naples FL / Pine TWP PA
I've run the gamut of different exhausts on stock, Stage 1, and hot rod motors. Anyone that tells you that TD's make the most power is misleading you at the very least. A good 2-1 will perform better than a true dual system. I've never said any different.
IF you had found a knowledgeable tune tech he could have adjusted your tune to make the most of your system no matter what it was. An incompetent tech's most often used answer is "those TD's are ruining your power".
Reading between the lines tells me that's likely what happened in your case too.
What a shame, 'cause you now have a pretty low regard for what is really a good exhaust system, particularly the stepped header versions.
Glad you like what you have now.
IF you had found a knowledgeable tune tech he could have adjusted your tune to make the most of your system no matter what it was. An incompetent tech's most often used answer is "those TD's are ruining your power".
Reading between the lines tells me that's likely what happened in your case too.
What a shame, 'cause you now have a pretty low regard for what is really a good exhaust system, particularly the stepped header versions.
Glad you like what you have now.
Outstanding HDF Member
Joined: Jun 2012
Posts: 2,248
Likes: 7
From: Atlanta, Georgia
Well I'm certainly not going to say the dealership techs knew what they were doing. And now we are getting into the long complicated story, but one set of techs, three of them were the lead techs at Zippers. They had my bike for two days and couldn't get it to work. They even tweaked their software and tore my throttle body apart found a minor problem and said we think we have it, but no, the problem only slightly improved. I can't really blame the TMax because there are sure a lot of them running around doing just fine, but the thing couldn't tune my motor with true duals on it and neither could the techs. If you hunt around this forum back to 2007 - 2008 I was not the only person having these issues. All this being said, going back to the factory head pipes resolved my issues as fast as they were created installing true duals. So I'm pretty much sticking with my position and what I was told that the true duals were ruining the engine's scavenging which I guess was pretty important on the stock 07s.
1. Place the stock headpipe back on or get a different one.
2. Get a cam built for the low end.
3. Go with more cubic inches.
4. Change the gearing so that it takes advantage of the new relocated power band.
You just chose to go with option 1, which wasnt a bad choice, but still shouldnt be your basis for saying that the true duals had something to do with it. I guarantee that had you went with option 2, 3, or 4, you would be singing a completely different tune right now. If you really want to know more about how scavenging works and about exhaust pulses and tuned pipes and why those headers were really stepped, just hit me up on a PM. You will find that a lot of information in this community is either totally false, or for lack of better words, total ignorance. Its hard for some folks with no experience with any sort of real speed and performance building to really understand how some of this stuff works. Good luck to you and enjoy!!
Outstanding HDF Member
Joined: Jan 2007
Posts: 2,598
Likes: 19
From: Naples FL / Pine TWP PA
Fair enough, but from my perspective, the rider, the true duals ruined the motor's performance. Since then I have learned a lot more about these motors and what works and what does not. I'm a hotrodder from way back. My experience with true duals was less than satisfactory. I didn't just throw my arms up and say these things suck. I spent a few thousand dollars and visited techs that were supposed to know what they were doing after I determined my dealership's techs were clueless to try and resolve the problems. While the power band may have moved it wasn't where I needed it to be on a touring bike. I will say my dyno numbers did not look good.
Outstanding HDF Member
Joined: Jun 2012
Posts: 2,248
Likes: 7
From: Atlanta, Georgia
One more note of advice...we dont ride the dyno. I can tell you that I have no clue as to what my bike makes on the dyno. I have a PC-V and autotune and have allowed it to do its thing and the bike runs great. Just my opinion...I cannot understand why anyone nowadays would visit a dyno or pay for a dyno for simple things like a Stage I or II. Now for all out motor builds or big bore kits, heads modifications, etc...yeah, dyno is worth it, but for simple intake/exhaust upgrades and cams too, the mail order tunes are perfectly acceptable. But hey...to each his own. Some folks chase numbers, while others chase performance. Go figure.
Outstanding HDF Member
Joined: Jan 2007
Posts: 2,598
Likes: 19
From: Naples FL / Pine TWP PA
I completely agree with this point. But what do you do when you can't resolve a performance issue? Stick it on a dyno and see where the problems are. It was pretty evident in this case. I don't believe in bench racing dyno numbers but they are good diagnostic tools and they are good for tuning a motor.
Cruiser
Joined: Dec 2012
Posts: 216
Likes: 1
From: peri,in
back in '79 i had 2 to1 exh. on my '74 FXE. i could unscrew one bolt & take off the exhaust, bungie tie it to the back rest * man!! that was the best sounding bike ever.
i would do this just outside Salt Lake City, ut, & head toward nevada. get close to
a city, stop & slip the muffler on again.
i would do this just outside Salt Lake City, ut, & head toward nevada. get close to
a city, stop & slip the muffler on again.
Outstanding HDF Member
Joined: Jan 2008
Posts: 3,328
Likes: 15
From: Pacific Northwest
Well I'm certainly not going to say the dealership techs knew what they were doing. And now we are getting into the long complicated story, but one set of techs, three of them were the lead techs at Zippers. They had my bike for two days and couldn't get it to work. They even tweaked their software and tore my throttle body apart found a minor problem and said we think we have it, but no, the problem only slightly improved. I can't really blame the TMax because there are sure a lot of them running around doing just fine, but the thing couldn't tune my motor with true duals on it and neither could the techs. If you hunt around this forum back to 2007 - 2008 I was not the only person having these issues. All this being said, going back to the factory head pipes resolved my issues as fast as they were created installing true duals. So I'm pretty much sticking with my position and what I was told that the true duals were ruining the engine's scavenging which I guess was pretty important on the stock 07s.
That's a long way from advising the OP that true duals will be the mistake of his young life. They just didn't work for your combination.
I also suspect they've updated the T-Max to cure some glitches found on early '07 systems.
Also one last point - there are plenty of 96" TC's running around with TD's having no problems whatsoever. My wife's bike is one of them.
Again, glad you found what works for you.
Outstanding HDF Member
Joined: Jan 2007
Posts: 2,598
Likes: 19
From: Naples FL / Pine TWP PA
True duals provide a performance loss. On the older bikes it looks better than the factory exhaust and provides a bit more passenger and rider comfort by getting some of the exhaust heat away from you. Two into one is the best for performance but they do not look too good on a bagger. A few companies have gone to slipons that kind of fake the two into one thing by making the left baffle high resistance. Fuel Moto is one company that does this.
And I agree, I knew plenty of people running them just fine back in 07. I don't know what else they did to their setup or they just didn't use sixth gear. For me I found needing to run at 80MPH or better to use 6th unacceptable. I'm also a bit **** about how my bike runs. I was also not the only person complaining about this issue. The best tune on my bike to date is me hand tuning it with the Power Vision. Runs like top. No pinging, no bogging down, I twist the throttle and hang on. Heck every once in a while I unintentionally lift the front wheel. Freaks me out a little when I do that.
Last edited by FX4; Jun 3, 2013 at 06:16 PM.
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Outstanding HDF Member
Joined: Jan 2008
Posts: 3,328
Likes: 15
From: Pacific Northwest
Splitting hairs there, don't ya think?
What conclusion do you think he's going to come to (and did) with a statement like "True duals provide a performance loss"?