After-market exhaust - Harley Davidson Street Forum - Street 500 and 750
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post #1 of 8 Old 09-15-2016, 03:38 PM Thread Starter
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After-market exhaust

My 2016 Street 750 came stock from the dealer with the Screamin' Eagle Nightstick slip on exhaust. Is any one familiar with the sound and performance difference between that and any of the other after market exhausts such as V&H, Two Brothers etc. I would like a bit more of the Harley sound from my bike but wasn't sure if the difference would be worth the extra money over what is already installed. When I do my 5000 mile service, I would like to get a new air intake and get the computer recalibrated but need to decide if I'm going to go with a new exhaust too so I can do it all at once.
Thanks for the help.
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post #2 of 8 Old 09-16-2016, 03:35 AM
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i seen a couple months ago a thread called "best slip on muffler? try to find that one . i got a firebrand on my 500 and it sounds more like a bigger twin hd than even those big hondas and yammys wannabes and yeah itll be worth the extra bucks popular suggestion on this forum is to get the bike computer flashed , especially if you get a new intake

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post #3 of 8 Old 09-16-2016, 05:02 AM
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Does your night-stick (it does sound rude doesn't it? ) have the 8 discs and end-cap?
Want more noise, remove the end-cap. ( I was lucky I just happened to have the tool to remove the screws).
I found it too noisy this way so I put a small washer between each of the discs to allow more air flow but left the end-cap on.
Just giving you ideas before you splash out on new slip-on.
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post #4 of 8 Old 09-16-2016, 11:27 AM
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The Street version of the Nightstick is (apparently) made by SuperTrapp for Harley. SuperTrapp sells a tuning kit that (according to this thread on SuperTrapp's forum) could be used to adjust the sound and power characteristics of the Nightstick.

The SuperTrapp tune-up kit that they mention is this one. I do not have any firsthand experience with it and cannot vouch that it is the proper one, I'm just going by what the other thread said.

From my reading on the SuperTrapp site, the general idea is more discs = louder. As for power, more discs = more top-end horsepower but less low-end torque, fewer discs = more low-end torque but doesn't make as much top-end HP.

Here's a quote from the SuperTrapp site:
Quote:
Removing discs decreases the exhaust opening and increases backpressure. This effectively decreases the powerband to create more low-end torque. It also decreases exhaust tone and enriches carburetion.

Adding discs increases the exhaust outlet and decreases back pressure. This widens the powerband at the top end. It also increases exhaust tone and leans out carburetion.
My take on this is that a stock Nightstick may not need an engine flash, but if you go adding discs to increase noise or top-end HP, you'll be leaning out the fuel mixture and reflashing the engine will become more and more necessary the more you deviate from stock. Of course, these bikes run lean already, so reflashing even with modest changes can provide benefits, I'm just saying that the less backpressure you have, the more necessary it'll be to "re-jet" (to use a term from the old carburetion days).

Last edited by Gaijin; 09-16-2016 at 11:30 AM.
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post #5 of 8 Old 09-17-2016, 03:29 AM
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sounds to me like just the opposite i cant see where adding things to an exhaust would decrease backpressure and make it run leaner or removing parts would make it run richer

madmike norfolk va 2015 street 500, 2009 yamaha vino
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post #6 of 8 Old 09-17-2016, 01:21 PM
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Well, it's explained in the quote -- adding discs makes the exit hole bigger, which decreases backpressure and then leans it out. You're adding more hole, more exit. Taking discs away makes the hole smaller, which increases backpressure.
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post #7 of 8 Old 09-17-2016, 06:34 PM
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FWIW
With the end-cap on, by having more discs you create more gaps / spaces between the discs for the exhaust gases to exit through.








Also did notice when I had mine off, the discs do have "trap" engraved/stamped on them.
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post #8 of 8 Old 09-19-2016, 01:11 PM Thread Starter
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Thanks guys. That all helps a lot.
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