Are GPR even trying with their underbody exhaust?

[SneakyOwl]

I just stumbled upon the GPR Exhaust Systems Deeptone Ghost @ Ebay. My initial thought was "Oh cool, another underbody exhaust".

But then I saw the pictures... I wonder how much time they spent making this.

 

[simpletty]

I just stumbled upon the GPR Exhaust Systems Deeptone Ghost @ Ebay. My initial thought was "Oh cool, another underbody exhaust".

But then I saw the pictures... I wonder how much time they spent making this.

View attachment 2775

looks like the tip of a honda generator exhaust....

 

[unicorn_violence]

its actually a pea shooter. its an added feature of the exhaust

 

[green_bread]

I believe the GPR exhaust is actually made for the Duke. When you order one for the RC, the only difference is you get the plate that covers the hole on the stock belly pan.

 

[Chris The Welder]

Probably sounds like a Honda generator.

 

[Formula390]

I just stumbled upon the GPR Exhaust Systems Deeptone Ghost @ Ebay. My initial thought was "Oh cool, another underbody exhaust".

But then I saw the pictures... I wonder how much time they spent making this.

View attachment 2775

It's actually making about 3HP less than stock with the exhaust on as well. Plus it's going to pop and run VERY lean down low without doing a PCv. You can put the Akra flash on the ECU which should fix it somewhat, but you'll still be lean without the PCv. I built a clone of the exhaust just to test to see how it performed and was VERY unimpressed.

 

[SneakyOwl]

Don't worry, I'm not getting it

 

[Chris The Welder]

Yeah, I don't think they will sell too many of these.

 

[Formula390]

The PowerCone was one of the first exhausts for the 390 motor... They have sold a lot of them, tho mostly overseas. The Duke is what it was targeted for, when (General statement) trend towards lesser experienced riders, those who are trying to save on purchases, and probably aren't as technicality savvy about these types of modifications. Without any modifications, or a piggy back to the ECU, it'll SLIGHTLY bump torque, but at the expense of HP.

Of course the airbox mod blows it out of the water, as does every other exhaust... With the exception of the Werks. I've been amazed by the numbers of folks who contacted me asking to buy the exhaust I designed, but never brought to market, because it failed to meet its goals for power, sound, and location. Some just wasn't the extra noise, power losses be damned. Back then I would tell them to look at the Werks, that I don't think they will be happy, but it's close enough to my design that they can run that.

Now we've got other options, with two undertail designs. Yosh and Tyga. I never liked the Yosh pipe. I feel it's scale isn't right to the bike. When may told me he was designing the dual exit, I was worried. I was wrong. He NAILED it! Everyone who's seen the exhaust in person comments how great it is for both looks and sound. Now, I sell the Tyga, so obviously my opinion is suspect as being biased, but I hope my reputation speaks to my honesty regardless of impact... The Tyga design is fucking AWESOME! It's matching the horsepower of the Akrapovic and Arrow, while being out of the way still. It's tone is guttural, and I'm noticing I'm not getting as much issue with drivers not noticing the bike ego are in earshot (yeah yeah, loud pipe save lives, I said it! LOL), and power is improved much over stock for torque and hp over stock. The one issue is it won't over rev as much as the Akra. That might be resolved with pulling the db killers, but that likely would cost HP. That type of testing on the street isn't conducive to keeping ones license, so I can't say definitively... But it's a safe bet. Dyno time would say for sure, but I didn't want to impose that much on Chad when he built the PCv map for the exhaust.

 

[Big_Muncho390]

It's good to know the Tyga exhaust performs well. I've had my eye on that exhaust and really like the look of the moto maggot over the stainless oval can with the carbon end cap.

 

[Dygear]

[P]ower is improved much over stock for torque and hp over stock. The one issue is it won't over rev as much as the Akra. That might be resolved with pulling the db killers, but that likely would cost HP. That type of testing on the street isn't conducive to keeping ones license, so I can't say definitively... But it's a safe bet. Dyno time would say for sure, but I didn't want to impose that much on Chad when he built the PCv map for the exhaust.

Please, impose on Chad. I want to see the numbers ... I'd also like to hear it vs the stock setup.

(Just a tad bit worried about burning the girl on the back of the bike with these.)

 

[Formula390]

Please, impose on Chad. I want to see the numbers ... I'd also like to hear it vs the stock setup.

(Just a tad bit worried about burning the girl on the back of the bike with these.)

The exhaust is back here and currently on the Formula390 test mule.

There are shields for the exhaust. I don't have them on the website yet as I just received them, but should be listing them soon. You wouldn't burn a passenger, but they would certainly notice the warmth.

I'm also planning on putting up some video at idle, standing still. Also some full throttle and decibel meter tests at speed to test noise levels for track purposes... But I'm sure it'll pass. It's more guttural than point blank loud. Certainly louder than stock, but not wake up the dead open pipe megaphone level.

 

[unicorn_violence]

The exhaust is back here and currently on the Formula390 test mule.

There are shields for the exhaust. I don't have them on the website yet as I just received them, but should be listing them soon. You wouldn't burn a passenger, but they would certainly notice the warmth.

I'm also planning on putting up some video at idle, standing still. Also some full throttle and decibel meter tests at speed to test noise levels for track purposes... But I'm sure it'll pass. It's more guttural than point blank loud. Certainly louder than stock, but not wake up the dead open pipe megaphone level.

if you do do some videos you should include a couple of that beautiful maggot exhaust! i really want to hear how that sounds

 

[Formula390]

if you do do some videos you should include a couple of that beautiful maggot exhaust! i really want to hear how that sounds

Unfortunately I had to pick which set if cans to use, and no matter which one I had, at least half would think I used the wrong ones. LOL

I have the problem tho of that to do that experiment, I'd need to essentially buy the cans. I obviously could no longer sell the cans as new if I used them for the test. Suffice to say however, the decibel asking shouldn't differ much between the two.

I'm going to make the video in the next few days. I have to wrangle up an assistant first tho. I can't do the riding and filming/decibel meter all by myself however.

 

[chrisdigital21]

It is actually loud as hell......seriously.... wish I never bought it.....

 

[chrisdigital21]

Probably sounds like a Honda generator.

If I had any idea how loud and shitty this thing sounded, I'd have spent the extra money on a Werkz system. I tried to run it with no pea shooter and I almost lost my hearing along with my whole city. My friends heare me 2 miles away. With the pea shooter in it, they only heard me form a mile away, lol. What a joke. Oh well. Time to make my own baffle and get it under control. Also the stock pipe clamp broke during installation.

 

[CDN Duke]

If I had any idea how loud and shitty this thing sounded, I'd have spent the extra money on a Werkz system. I tried to run it with no pea shooter and I almost lost my hearing along with my whole city. My friends heare me 2 miles away. With the pea shooter in it, they only heard me form a mile away, lol. What a joke. Oh well. Time to make my own baffle and get it under control. Also the stock pipe clamp broke during installation.

Chris, any chance you can post a video of the GPR ghost?

I would consider the high mount duals as an alternative, won't do side mount, but I don't think they fit the Duke 390s, particularly if I want to retain rear pegs...

 

[chrisdigital21]

I will Have a video Up tomorrow for you. I will explain what i did today to help it sound a tad better. Cheers

 

[CDN Duke]

The PowerCone was one of the first exhausts for the 390 motor... They have sold a lot of them, tho mostly overseas. The Duke is what it was targeted for, when (General statement) trend towards lesser experienced riders, those who are trying to save on purchases, and probably aren't as technicality savvy about these types of modifications. Without any modifications, or a piggy back to the ECU, it'll SLIGHTLY bump torque, but at the expense of HP.

Of course the airbox mod blows it out of the water, as does every other exhaust... With the exception of the Werks. I've been amazed by the numbers of folks who contacted me asking to buy the exhaust I designed, but never brought to market, because it failed to meet its goals for power, sound, and location. Some just wasn't the extra noise, power losses be damned. Back then I would tell them to look at the Werks, that I don't think they will be happy, but it's close enough to my design that they can run that.

Now we've got other options, with two undertail designs. Yosh and Tyga. I never liked the Yosh pipe. I feel it's scale isn't right to the bike. When may told me he was designing the dual exit, I was worried. I was wrong. He NAILED it! Everyone who's seen the exhaust in person comments how great it is for both looks and sound. Now, I sell the Tyga, so obviously my opinion is suspect as being biased, but I hope my reputation speaks to my honesty regardless of impact... The Tyga design is fucking AWESOME! It's matching the horsepower of the Akrapovic and Arrow, while being out of the way still. It's tone is guttural, and I'm noticing I'm not getting as much issue with drivers not noticing the bike ego are in earshot (yeah yeah, loud pipe save lives, I said it! LOL), and power is improved much over stock for torque and hp over stock. The one issue is it won't over rev as much as the Akra. That might be resolved with pulling the db killers, but that likely would cost HP. That type of testing on the street isn't conducive to keeping ones license, so I can't say definitively... But it's a safe bet. Dyno time would say for sure, but I didn't want to impose that much on Chad when he built the PCv map for the exhaust.

While the stock exhaust is short in external dimensions, the internal tube length appears to be key for maintaining power - KTM went to great lengths (pun intended) in tuning for power I expect. Recognizing a desire to not have a side mount, I wonder if anyone has a 'lengthy' option that fits in the stock location, or a high mount that retains rear pegs on a Duke...

I may take another look at the one of the exhaust lobotomy threads and see if I can get an estimate locally for replacing the stock cat (only) with more tube to retain the tuned length and see that does for increased tone at a reduced cost with hopefully negligible impact on HP. I'm running the Akra map now with plans to install the MNNTHBX airbox lid when it arrives.

 

[chrisdigital21]

While the stock exhaust is short in external dimensions, the internal tube length appears to be key for maintaining power - KTM went to great lengths (pun intended) in tuning for power I expect. Recognizing a desire to not have a side mount, I wonder if anyone has a 'lengthy' option that fits in the stock location, or a high mount that retains rear pegs on a Duke...

I may take another look at the one of the exhaust lobotomy threads and see if I can get an estimate locally for replacing the stock cat (only) with more tube to retain the tuned length and see that does for increased tone at a reduced cost with hopefully negligible impact on HP. I'm running the Akra map now with plans to install the MNNTHBX airbox lid when it arrives.

Just Wait till you see my video. I am not saying the GPR system bad performance wise, Just way loud. I currently have PCV with a custom map (currently a work in progress) running and using a 16t front sprocket. Look out for my video soon. Hope to have another this weekend. Cheers