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Discussion Starter · #1 · (Edited)
I managed to get a hold of a SC Project slip on exhaust (no cat delete) for my Duke 390 2nd gen bike.
  • Do I need to buy a piggyback controller if I change the slip on?
  • Will it work fine on stock?
  • Will a Booster plug or Rapid bike easy be enough for a slip on exhaust if i need to change the fueling?
This is my first motorcycle so I don't know the ins and outs of exhaust and fueling yet. Thanks in advance!
 

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I myself have just purchased a new 390 duke and the dealer has told me the slip on muffler can be done without a remap. If using an akrapovic slip on I can still retain the factory warrenty
 

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In general, if ONLY replacing the end can you should be okay without a piggyback/booster-plug.
As Matt mentioned the PowerParts Akrapovic will have you keep the warranty (not any spinoff Chinese Akra from the on-line aftermarket suppliers).
Another thing you need to bear in mind is that you most likely loose on power and torque changing to the SC Project can.
 

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Discussion Starter · #4 ·
In general, if ONLY replacing the end can you should be okay without a piggyback/booster-plug.
As Matt mentioned the PowerParts Akrapovic will have you keep the warranty (not any spinoff Chinese Akra from the on-line aftermarket suppliers).
Another thing you need to bear in mind is that you most likely loose on power and torque changing to the SC Project can.
Does losing that power and torque have a negative effect on the engine?
 

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That is a very good question to which I have no direct answer.
 

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Does losing that power and torque have a negative effect on the engine?
The stock tuning is too lean in order to meet emission standards. I added a wide gauge o2 sensor to tune my bike. I bought a piggyback and used potentiometers to adjust stock sensor to read leaner, therefore making bike run richer in open loop. I adjusted one for sport riding to afr 13.5, which fixes the below 4500rpm stuttering/jerking. The other is adjusted for better gas milage to 14.7 I partioned my map with R-Tune and made 6200 to 6400 richer by 15% to get rid of a flat spot near 3/4 to full throttle. The rest of closed loop is adjusted from 13.5 to 12.9 at higher rpm/load for more power. Its still not perfect but I will do data logging next year to get it spot on. My bike rips and is smooth at all throttle and rpms now.
Making any changes will change the mixture. Nobody knows how much or where it will change unless you measure it. My premuffler and cat delete caused the wide open throttle to run richer by about 7%. If it became 7% leaner instead, motor damage could occur.
Either do what I have done, get a dyno tune, or simply buy something like a Rapid Bike Easy or Booster Plug.
 

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Does anyone have the Competition Werkes slip on exhaust for their bike? If so, does it reduce power and torque? I’m considering getting one, but based on what I’ve read on these threads is that it seems like most slip on exhausts reduce power. Does deleting the chamber help with power loss? Im new here, and trying to learn as much as i can about my new 2020 390 Duke.
 

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I deleted cat and chamber( with Werkes)and kept stock muffler. Its a lot louder. I like it but have to be be consious to let off throttle around people and passing cars.
My wide band afr meter showed running 5% too rich wide open. That would reduce power. If it went lean instead, engine damage can happen.
I adjusted afr to 12.8 -13.2 with Powertronic.
There fore if you remap you probably get more power, less if its not remapped.
 

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In general, if ONLY replacing the end can you should be okay without a piggyback/booster-plug.
As Matt mentioned the PowerParts Akrapovic will have you keep the warranty (not any spinoff Chinese Akra from the on-line aftermarket suppliers).
Another thing you need to bear in mind is that you most likely loose on power and torque changing to the SC Project can.
Hi,

Do the loss of torque and power will appear with any brand of slip on ? Is the stock the best option for keep power and torque ?
 

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As for the pretty long history of people trying different exhaust set-ups the tendency is such that the vast majority of aftermarket systems lose power and torque.
Some systems equal the OEM system and only a hand full seem to increase power marginally (3 HP or so).
I am mainly talking about the first Generation bikes with the tea-pot underbelly exhaust and would think that the second generation bikes will not be affected as much as the older designs.
Proven exhaust systems, with dyno runs and such, are the OEM Akrapovic and TYGA setup.
I am not aware of any other system that improves power and torque for road use.
In my view, this industry thrives on esthetics and feeling (more noise = more power).
My 2 cents.
 

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Dyno testing I’ve seen on gen 2 suggests that deleting cat on gen 2 can show an increase in power but deleting the presilencer loses mid range torque.
 

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What increase you've seen in BHP on the second generation 390s with the catalyst removed Marius?

Dyno testing I’ve seen on gen 2 suggests that deleting cat on gen 2 can show an increase in power but deleting the presilencer loses mid range torque.
 
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